The effects of fire* are various, It heats, it shines, it expands, it dissolves other bodies, either by melting or reducing them to ashes or calx. Most of these argue a vehement motion of its particles, which tears asunder whatever it seizes. It seems to be a most subtle matter, dispersed throughout the universe. Yet this, even when collected, soon scatters again, unless it be detained by some inflammable matter, Not that fire will spring from every motion: it must be circular, as well as rapid. For if particles move ever so swift in a strait line, no fire will follow.

* It should here be understood, that by the terms fire, pure fire, elementary fire, &c. as they are here used, is meant, the basis or matter of heat, fire, flame, &c. which in the new chemical nomenclature is termed caloric. This is an elementary substance of so subtle a nature, that it penetrates all bodies, but in different quantities, and under different circumstances, according to the quantity present, and according to the capacities of bodies to receive it. It may be concentred in such quantities, and consequently to such degrees of intensity, as to destroy or dissipate all known substances. All bodies are capable of sustaining a certain quantity without their destruction. Indeed a certain proportion is necessary, and indispensable to the existence of all bodies; and it is highly presumable, that it could not be entirely eradicated from any body, under any possible circumstances. These facts, however, are well known ; that it can be concentred in most intense degrees, that it can occupy all bodies in vastly different proportions; that different bodies demonstrate very different capacities for it; that some are more powerful conductors of it than others; and that all bodies can endure a certain degree of it, and still retain their coherence: but beyond that degree, they suffer disorganization and destruction, and are reduced to calces, ashes, or vapour.

Caloric is a substance which pervades all bodies, even every particle of the air, and the earth; and it rushes with a velocity proportioned to its degree of intensity, to supply an equal temperature. It remains fixed in all bodies, and perhaps the degree of its fixidity constitutes the capacity of combustion, and the capacity of enduring it in certain degrees of intensity; and would it not hence appear plausible that those substances wherein this capacity existed in the least degree, would become the most powerful conductors of it. It exists abundantly in wood, hence wood is a poor conductor. It exists abundantly less in metals, hence metals are more powerful conductors of it, and this would appear in proportion to the sense of different degrees of coldness, in the different substances, as metals feel so much colder than wood.

Heat seems to be nothing but motion: but this motion has some peculiar circumstances. 1. It is expansive motion, whereby a body endeavours to dilate itself. 2. This motion is upward, and toward the circumference. 3. It is not an equable motion of the whole, but only of the smaller particles of the body. 4. It is a rapid motion. Heat may therefore be defined, an expansive, undulatory motion in the minute particles of a body, whereby they rapidly tend to the circumference, and at the same time upward.

Fire has some effect on most bodies, even in an exhausted receiver. One placed a black ribbon therein, and then applied a burning-glass. Abundance of smoke issued out of it, which fell by little and little, and

Caloric cannot be confined by any means, hence it is ranked among the unconfinable elements. Its exclusive office seems to be to unite with other bodies, to capacitate them; to give them the powers of motion, and to qualify them for their infinite variety of operations in nature. It cannot exist in an independent state, but it is observable, that it has its degrees of affinity. It naturally exists in smaller quantities in some bodies, than others, and probably it approaches more towards an abstract and independent character in electricity, than in any other state; though it appears to be a physical impossibility to separate it entirely from other elementary matter, yet by what subtle substances it is retained in the Leyden phial, it appears an equal impossibility to ascertain; however, we may safely conclude that light is one of those substances, but there appears to be a third substance something like magnetism, which gives polarity to electricity. Whatever it may be, it appears to be a latent gass combined with oxygen, and which is set at liberty by its decomposition, and we constantly observe in electricity the correspondent characteristics of the tripple compound, the effects of caloric, the velocity of light, and the power of magnetism.

Hot and cold we say, and apply the epithets on various occasions, but these are mere local circumstances of comparative quantities: there is neither heat nor cold in equal temperature, lithe one body in contact, is charged with a greater quantity of caloric than the organs of sensation, or the other body, the consequent sensation or effect, we term heat, or the effect of heat to that body. But it should be remembered, that it is cold, or the effect of cold, to the other body; for the reciprocal effect is in a duplicate ratio. If we instance the effects of caloric in water, we shall be presented with an illimitable gradation of consequences. It may be so abundantly charged with caloric beyond its capacity, as to be thrown into the most violent agitations, and fly off in prodigious quantities, in the form of vapour, with astonishing powers. It may be charged in other variable degrees, so as to be what we term hot, warm, lukewarm, &c. It may be reduced to an equal temperature, and then it will be neither hot nor cold; it may be reduced in degrees on the other extreme, from the mean of equal temperature, and then it will be cold very cold, intensely cold, &c. and this diminution may be carried on to still greater degrees, insomuch that the particles of water will be distended, and reduced from their calorific menstruation, to actual cohesion, and become a solid body; which from the distension of its particles, will occupy a greater space than in the liquid form. Water thus reduced to a state of solidity we call ice; even in this state it is not to be supposed that the water is entirely divested of caloric, but that the quantity of caloric as a cause, is so variously reduced, as to produce the various effects.

the ribbon appeared not at all changed. But when it was touched, after the re-admission of the air, it presently fell into ashes.

The glass being applied to gunpowder so enclosed, it burnt grain by grain, but none of the grains kindled. Another time when the sun had less force, they would not burn, but only boiled and emitted smoke. This smoke failing on the board on which the powder lay, was of the colour of brimstone. The powder that remained, being put on coals, burned like saltpetre, inasmuch as the brimstone had exhaled.

Tin and copper melted together weigh more than both bodies did before. Yea, orpin being mixed with salt of tartar, is heavier by a fifth part.

To account for this, it has been commonly supposed. that fire adds to the weight of bodies. But fire has itself no weight at all: therefore it can give none. Pure fire, as Dr. Hillary observes, is a body without gravity, and has no more tendency to any one part of space, than to another.

Is not then this alteration of weight rather owing to an alteration of the inward texture of the particles in the body calcined The lighter particles being removed by exhalation, do not those remaining approach nearer each other And must not then the weight, which is always as the solidity, increase accordingly *

It seems strange, to talk of heating cold liquors with ice. Yet it may easily be done thus. Out of a basin of cold water, wherein several fragments of ice are swimming, take one or two, and plunge them into a wide-mouthed glass of strong oil of vitriol : this quickly melts the ice, and by two or three shakes, the liquor grows so hot, that frequently you cannot endure to hold the phial in your hand.

It may seem as strange, that those parts of the earth which are nearest the sun should be intensely cold. Yet so it is. For the higher you ascend on mountains, the colder is the air. And the tops of the highest mountains in the most sultry countries are eternally clothed with snow. This is partly owning to the thinness of the air, and partly to the little surface of earth there to reflect the solar rays

* It is now ascertained, that bodies in combustion, absorb oxygen, and that the increase of their weight is exactly equal to the quantity of oxygen decomposed. Metals by fusion are reduced to oxide, and they are restored to the metalic state by fusion with substances which have a more powerful attraction for the oxygen than the metals. Charcoal is of this description. In this case the oxides lose that proportion of weight which they had gained by the process of oxydation.

Oil of vitriol, or as is more properly termed in the new nomenclature, sulphuric acid, has so powerful an attraction for water, and decomposes it with such facility, as to give out a prodigious quantity of heat, insomuch as to make the water boil furiously if mixed in the due proportions, which is about 1 to 3.

This is a fact, which shows that heat does not travel to us from the sun. Caloric is unquestionably a constituent elementary part of our globe, and is attached to it, and does not travel far into the atmosphere; it is an elementary substance

Very different degrees of heat, obtain in the same latitude, on the different sides of the South American continent: which shows that the temperature of a place depends much more upon other circumstances, than upon its distance from the pole, or nearness to the equinoctial. Thus though the coast of Brazil is extremely sultry, yet the coast of the South seas, in the same latitude, is quite temperate, and in ranging along it, one does not meet with so warm weather, as is frequent in a summer’s day in England : which is the more extraordinary, as there never falls any rain to refresh and cool the air. On the coast of Peru, even under the line, every thing contributes to make the day agreeable. In other countries, the scorching sun in summer, makes the day unfit either for labour or amusement: and the rains are no less troublesome, in the cooler parts of the year. But in this delightful climate the sun rarely appears; for there is constantly a gray, cheerful sky, just sufficient to screen the sun, without obscuring the air. Thus all parts of the day are proper for labour, while the coolness produced elsewhere by rains, is here brought about by fresh breezes from the cooler regions.

This is chiefly owing to the Andes, which running not far from, and nearly parallel with the shore, and rising immensely higher than any other mountains in America, form on their sides a prodigious tract of land, where, according to their different heights, all kinds of climates may be found, at all seasons of the year. These mountains intercept great part of the eastern winds, which generally blow on the continent of America, coal that part of tile air which comes over their tops, and keep it cool by the snows, with which they are always covered. Thus by spreading the influence of their frozen crests, to the neighbouring coasts and seas, the cause the temperature and equability which constantly prevail there. But when they leave these mountains, they experience in a short time an entire change of climate, and in two or three days pass from the temperate air of Peru, to the sultry atmosphere of the West Indies.

The sparks which appear on striking fire with a flint and steel, are discovered by the microscope, to be so many spherical balls of iron, detached by the blow from the mass. They are then red hot. After they cool, they are a sort of scoriae or dross.

2. Fire is generated chiefly, either by collecting the sunbeams by a glass., or by rubbing hard bodies against each other. Either way, the subtle matter is collected from all sides, and put into a rapid, circular

which is put in motion by the force of attraction, and consequently it will be the most concentred in the atmosphere, where that force is greatest, and that is under the equator; but even here its degrees of concentration will depend on the degrees of elevation from the surface of the earth, for that may be so great as to penetrate the regions of intense cold.

motion. This continues together, as long as it is supplied with inflammable substances. The particles of these being divided by the fire, are scattered hither and thither, and the fire goes out unless fresh fuel be brought: as it does if air be wanting. For as that subtle matter is dissipated continually, it soon fails, unless recruited from the air. If water or dust be thrown upon fire, it is likewise quickly extinguished. For these interrupt that internal motion which is essential to it.

That fuel cannot consume without air, is clearly proved by an easy experiment. Let a strong hollow cylinder of iron, be fitted with a firm screw at each end. Enclose in this a piece of charcoal: then screw up both ends, and place it in a strong fire. Let it stay there as long as you will. Open it when cool, and the charcoal is no way diminished.* It is plain from this, that the consumption of fuel depends upon the rarefaction and agitation of its parts by fresh air. And hence when we have the reason of the known method of extinguishing fires by smothering them.

3. The watery parts of the fuel being rarified by the heat, ascends in the form of smoke, carrying with it many of the lighter particles which, adhere as soot to the chimney. The grosser and more compact the contexture whereof the fire cannot wholly destroy, remain and constitute ashes, which are of consequence extremely porous, all that was combustible in it being consumed.

To enlarge a little on this subject. Fire is a body, and a body in motion. It is in motion: for it expands the air, which can no otherwise be done, than by communicating motion to it. - And that it is a ‘body appears hence. Pure mercury enclosed in a phial, and kept in a gentle heat for a year, is reduced into a solid; and its weight is considerably increased, which can only spring from the accession of fire.

Fire is the instrument of all the motion in the universe. Without it all bodies would ‘become immoveable. Men would harden into statues: and not only water, but air cohere into a firm, rigid mass.

As it is in itself, it is termed ELEMENTARY FIRE: joined with other bodies, it is called CULINARY. The minute particles of this, joining with those of the pure fire, constitute what is termed FLAME. Pure fire, such as is collected by a burning-glass, yields no flame, smoke, or ashes. In itself it is imperceptible, but is discovered by its effects. The first of these is HEAT, which arises wholly from fire, and the mea

* The coal in this situation could not consume, because it is deprived of oxygen, the air, which abounds with oxygen, being excluded, the coal must remain una]tered even in the most intense heat; but convey a stream of pure oxygen gass into the tube, and its consumption would be more rapid than by the common atmospheric air. Oxygen is a grand, constituent, elementary principle of lire, and no combustion could possibly take place without it.

By all these expressions is evidently meant the basis of fire, flame, heat. smoke. &c. which, as already observed, is termed caloric.

sure of heat is always as the measure of fire. The second is DILATATION in all solid, and RAREFACTION in all fluid bodies, So an iron rod, the, more it s heated, increases the more in all its dimensions; and by the same degrees that it cools, it contracts, till it shrinks to its first magnitude. So gold, when fused, takes up more space than it did before. And mercury ascends in a hollow tube over the fire, to above thirty times its former height. The same degree of heat rarefies fluids sooner, and in a greater degree, than it does solids; and the lighter the fluid, the more it is dilated. Thus air, the lightest of all fluids, expands the most, The third effect of fire is MOTION: for in dilating bodies, it must needs move their parts. All motion springs from it. Only take fire away,, and all nature would grow into one concrete, solid as gold, and, hard as diamond,

Pure fire needs no air to sustain it. Put calx of tin into an exhausted receiver, and if you apply a burning-glass, the calx will be so vehemently dilated, as to break the receiver into a thousand pieces.

All the effects of elementary fire may be increased. 1. By rubbing one body against another. And the more hard and solid the bodies are, the more heat is produced. So sponges rubbed together, acquire little or no heat: but two pieces of iron, an intense heat. 2. By mixing certain bodies together. So steel filings, mixed with oil of cloves or spirit of nitre, grow exceedingly hot; yea, burst into a violent flame.

Yet it does not appear that any new fire is generated in any of these ways. Friction does not create fire, but only collect what was before dispersed. It is present every where, in all bodies, in all space, at all times, and that in equal quantities.5 Go where you will, to the highest mountain, or the deepest cavern, by one or other of these ways lire may be collected. Yea, there is no place in the world, where the attrition of two sticks will not make it sensible.

But in what manner soever fire is collected, if the collecting cause cease, it disappears again, unless it be supplied with fuel, and then it

* The element of lire does not appear to be uniformly diffused; though it has an invariable tendency to diffuse itself uniformly; but it appears to be diverted from this tendency, by its affinities to the variable capacity of matter. Caloric has been known to be concentred so abundantly in the air, as spontaneously to set on fire combustible bodies. We have instances on record, of the ripe harvest being set on fire by the excessive heat of the weather. In Africa and some parts of Asia, where certain winds blow, it concentres in streaks of liquid fire, and whatever animal breathes the ethereal flame it instantly dies. All the animals in the district give notice of its approach by cries of distress, and they stand with their noses to the earth to avoid the deadly blast. The inhabitants shut themselves up in their houses, and dare not venture abroad, until the flaming breeze has past. Hence it appears, that caloric is variously concentred, by various circumstances and is not uniformly diffused through nature.

becomes culinary fire. By fuel we mean whatever receives and retains fire, and is consumed thereby. The only fuel in nature is oil or sulphur, and bodies are only fuel, as containing oil. Hence, 1. Alt vegetables,, not too moist or too dry, affords fuel, particularly those which contain much oil, as balsamic and resinous woods. 2. All vegetable and animal coals, being those parts which have exhaled their water and salt, and retained the oil alone inhering in the earth. 3. All bituminous earth. 4. All mineral sulphur, whether pure or joined with other things. 5. The fat and dung of animals: and, 6. Chemical oil and spirits.

On the removal of air, this fire goes out. Yet it does not immediately bear the air, but repels it, and by that means forms a kind of vault, which by its weight, and the pressure of the incumbent air, confines the particles that would otherwise. escape, and applies them to the combustible matter. Hence the heavier the air, the fiercer the fire; which therefore is fiercest in still, cold weather.

The fire in’ burning combustible matter, affords a shining fire or flame, or both and frequently too, smoke, soot and ashes. Shining fire seems to be elementary fire, so strongly attracted toward the particles of the fuel, as to whirl, divide, attenuate them, and thus render them volatile, and just fit to be expelled. Flame seems to be the most volatile part of the fuel, greatly rarefied and heated red hot. Soot is a sort of coal, consisting of a thick sulphur, and an attenuated oil, with earth, and salt. Smoke is the earthy and watery particles of the fuel, so rarefied as to break through into the atmosphere. Ashes are the earth and salt, which the fire leaves unchanged.

Fire increases the weight of some bodies. Thus if antimony be placed under a burning-glass, the greatest part of it will seem to evaporate in fumes, and yet if it is weighed, it will be found to have gained in weight.

But beside the solar, there is a subterraneous lire. The earth is only cold to the depth of forty or fifty feet. Then it begins to grow warmer; and at a great depth it is so hot as to destroy respiration.* Hence we learn that there is another source of fire, or as it were another sun in the bosom of the earth.

Upon the application of fire to water, it boils: that is, the particles of fire, passing through the pores of the vessel, strike on the lowest particles of the water, impel them upwards, and render them lighter than before, both by inflating them into little vesicles, and by breaking and separating their spherules. There will of consequence be a constant flux of water, from the bottom of the vessel to the top. And hence we see, why the water is hot at the top, sooner than at the bottom.

*This consequence is not uniform, for it is found, by experience, that there are as well as hot currents of air, and water, in the bowels of the earth; and that the absence of oxygen is the cause of the destruction of respiration.

Farther, the air contained in the interstices of the water being dilated, and its spring increased by the heat, it ascends through the water into the air, carrying with it the contiguous particles of water. And by this means much of the water will be heaved up, and let fall alternately, as the air has no power to carry away into the atmosphere more than that small part that rises in the steam.

4. That this subtle matter is plentifully collected in the bowels of the earth, appears from burning mountains. It is observed, that there is always in the neighbourhood of these, plenty of sulphur or bitumen, the stench whereof spreads far and near, especially before any great eruption. This feeds the fire, which maybe kindled by various means, so as to continue for many centuries. AEtna and Vesuvius have burned for above two thousand years, and probably will till the end of time.

5. Mount Aetna is divided into three distinct regions, called La Regione Culta, the Fertile Region; La Regione Sylvosa, the Woody Region; and La Regione Deserta, the Barren Region.

The three are as different, both in climate and productions, as the three zones of the earth: and perhaps with equal propriety might have been styled the torrid, the temperate, and the frigid zones. The first region surrounds the foot of the mountain, and constitutes the most fertile country in the world, on all sides of it, to the extent of about forteen or fifteen miles, where the woody region begins. It is composed almost entirely of lava, which, after a number of ages, is at last converted into the most fertile of all soils.

Every eruption generally forms a new mountain. As the great crater of Aetna itself is raised to such an enormous height above the lower regions of the mountain, it is not possible that the internal lire raging for vent, even round the base, and no doubt vastly below it, should be carried to the height of twelve or thirteen thousand feet to the summit of Aetna. It has therefore generally happened, that after shaking the mountain and its neighbourhood for some time, it at last bursts open its side. At first it only sends forth a thick smoke and showers of ashes, that lay waste the adjacent country: these are soon followed by red hot stones, and rocks of a great size, thrown to an immense height in the air. The fall of these stones, together with the quantity of ashes discharged at the same time, at last form one of these spherical and conical mountains. Sometimes this process is finished in the course of a few days: sometimes it lasts for months, which was the case in the eruption in 1669. In that case the mountains formed are of a great size; some of them are not less than seven or eight miles round, and upwards of one thousand feet in perpendicular height; others are not more than two or three miles round, and three or four hundred feet high.

After the new mountain is formed, the lava generally bursts out from its lower side; and bearing away every thing before it, is for the most part terminated by the sea. This is the common progress of an eruption! however, it sometimes happens, though rarely, that the lava bursts at once from the side of the mountain, without all these attending circumstances: and this is commonly the case with the eruption of Vesuvius, where the elevation being so much smaller, the melted matter is generally carried up into the crater of the mountain, which then discharges showers of stones and ashes from the mouth of the volcano, without forming any new mountain, but only adding considerably to the height of the old one; till at last the lava, rising near the summit, bursts the side of the crater, and the eruption is discharged. This has been the case with two eruptions lately; but Aetna is upon a much larger scale, and one crater is not enough to give vent to such oceans of liquid ‘fire.

A Sicilian gentleman saw, in an eruption of that mountain, large rocks of fire discharged to the height of some thousand feet, with a noise more terrible, than that of thunder. He measured, from the time ‘of their greatest elevation till they reached the ground, and found they took twenty-one seconds to descend, with (the spaces being as the squares of the times) amounted to upwards of seven thousand feet.

After contemplating these objects for some time, says a late traveller, we set off, and soon after arrived at the foot of the great crater of Aetna. This is of an exact conical figure, and rises equally on all sides. It is composed solely of ashes, and other burnt materials, discharged from the mouth of the volcano, which is in its centre. This conical mountain is of a very large size; its circumference cannot be less than ten miles. Here we took a second rest, as the greatest part of our fatigue still remained. The mercury had fallen to 20. 4 1/2 We found this mountain excessively steep; and although it had appeared black, yet it was likewise covered with snow; but the surface, luckily for us, was spread over with a pretty thick layer of ashes, thrown from the crater. Had it not been for this, we never should have been able to come to the top.

The circumference of this zone, or great circle on AEtna, is not less ‘than seventy or eighty miles. It is every where succeeded by the vineyards, orchards and corn fields, that compose the Regions Cults, or the Fertile Region. The last zone is much broader than the others, and extends on all sides to the foot of the mountain. Its whole circumference is 183 miles.

The present crater of this immense volcano is a circle of about three miles and a half in circumference. It goes shelving down on each side, and forms a regular hollow, like a vast amphitheatre. From many places of this space, issues volumes of sulphureous smoke, which being much heavier than the circumambient air, instead of rising in it, as smoke generally does, immediately on its getting out of the crater, rolls down the side of the mountain like a torrent, till coming to that part of the atmosphere of the same specific gravity with itself, it shoots off horizontally; and forms a large tract in the air, according to the direction of the wind: which, happily for us, carried it exactly to the side opposite to that where we were placed. The crater is so hot that it is very dangerous, if not impossible, to go down into it: besides the smoke is very incommodious, and in many places the surface is so soft,, there have been instances of people sinking down into it, and paying for their temerity with their lives. Near the centre of the crater is the great mouth of the volcano, that tremendous gulf so celebrated in all ages. We beheld it with awe, and with horror, and were not surprised that it had been considered as the place of the damned. When we reflect on the immensity if its depth, the vast cells and caverns whence so many lavas have issued; the boiling of the matter, the shaking of the mountain, the explosion of flaming rocks, we must allow that the liveliest imagination hardly ever formed an idea of hell more dreadful.

Kircher pretends to have measured it, and to have found it four thousand French toises in height; which is more than any of the Andes are. The Italian mathematicians are still more absurd. Some of them make it eight miles, some six, and some four. Arnici, the last, and I believe the best who has made this attempt, reduces it to three miles two hundred and sixty-four paces; but even this must be exceedingly erroneous, and probably the perpendicular height of Aetna is little more than two miles.

It is a curious consideration that this mountain should re-unite every beauty and every horror: and, in short, all the most opposite and dissimilar objects in nature. Here you observe a gulf, that formerly threw out torrents of fire, now covered with the most luxuriant vegetation; and from an object of horror becomes one of delight. Here you gather the most delicious fruits, rising from what was lately a black and barren rock. Here the ground is covered with every flower; and we wander over these beauties, and contemplate this wilderness of sweets without considering that hell and all its terrors are immediately under our feet, and that but few yards separate us from lakes of liquid fire and brimstone.

But our astonishment still increases, on casting our eyes on the higher regions of the mountain. There you behold in perpetual union, the two elements that are at perpetual war; an immense gulf of fire, for ever existing in the midst of snows, which it has not power to melt; and immense fields of snow and ice for ever surrounding this gulf of lire, which they have not power to extinguish.

The quantity of matter discharged from Aetna is supposed, upon a moderate computation, to exceed twenty times the original bulk of the mountain. The greatest part of Sicily seems covered with its eruptions. The inhabitants of Catanea have found, at the distance of several miles, streets and houses, sixty feet deep, overwhelmed by the lava or matter it has discharged: nay, the walls of these very houses have been built of materials evidently thrown up by the mountain. The inference is obvious: that the matter thus exploded cannot belong to the mountain itself: otherwise it would have been quickly consumed; it cannot be derived from moderate depths: since its amazing quantity evinces that all the places near the bottom, must have long since been exhausted: it must therefore be supplied from the deeper regions of the earth, the undiscovered tracts, where the Deity performs his wonders in solitude.

An eruption of Mount Aetna, in 1669 was preceded, for eighteen days, with a dark, thick sky, thunder, lightning, and frequent tremblings of the earth. The place of eruption was twenty miles from the old mouth: the matter of it was a stream of melted minerals, boiling up and gushing out, as water does at the head of a great river. Having run thus for more than a stone’s cast, the extremeties began to crust, anti turn into porous stones, resembling, huge cakes of sea coal, full of a fierce fire. These came rolling over one another, and where any thing opposed, filled up the space and rolled over. But they bore down any common building, and burnt up all that was combustible. This inundation went on about a furlong a day, for nineteen or twenty days. It overwhelmed fourteen towns and villages. The noise of the eruption was heard sixty miles.

On Sunday, March 9, 1755, about noon, Mount Aetna began to cast from its mouth a great quantity of flame and smoke, with a most horrible noise. At four o’clock the air became quite dark and covered with black clouds. At ‘six a shower of stones, each weighing about three ounces, began to fall all over the’ city of Mascali and its territories. This shower lasted till a quarter past seven; and was succeeded all night by a shower of black sand. On Monday morning at eight, there sprang from the bottom of the mountain a river of scalding hot water, which, in half a quarter of an hour, overflowed all the rugged land that is near the foot of the hill, and suddenly going off, left the whole a large plain of sand. The stones and sand which remain wherever this water reached, differ in nothing from the stones and sand of the sea, and have even the same saltness. After the water was gone there sprang from the same opening a small stream of fire, which continued for twenty. four hours. On Tuesday, about a mile below this opening, there arose another stream of fire, which being in breadth about four hundred feet, overflowed all the adjacent country.

6.On the 3d of December, 1754. a stream of liquid fire began to run down the side of Mount Vesuvius, from an opening on the east side. But it soon ceased running from this orifice, and burst out from a much larger one, about two hundred yards below it. Afterward it burst out from a third orifice, and having ran for some space with great fury, the surface then began to cool and incrust, as it ran over gently declining ground, till it came within about ten yards of the top of a steep declivity. Here the fire collected, as in a reservoir, to supply a cascade, which rushed down from thence in a channel of more than twenty feet wide, and about two hundred yards in length, with a fall of at least fifty feet. After this the stream was less rapid, but grew wider, and spread several miles from its source. It now presented a very different scene from what it afforded before. The cascade, says an eye witness, looks like melted gold, and tears off large bodies of old lava (so they term the incrustation) which float down the stream, till the intenseness of the heat lifts them from the bottom. But in the lower country, it divides into smaller streams, running with less rapidity: and yet with such violence, that it drives the strongest stone fences before it, and lighting the trees like torches, afford a most extraordinary, though dismal spectacle.

On December 23, 1760, about two in the morning, a violent shock of an earthquake was felt near Mount Vesuvius. Some time after, some countrymen being at work, four or five miles from it, perceived the ground near them on a sudden heave and gape, like dough that is rising. At the same time they observed smoke issuing from the clefts. They immediately fled, till they thought they were out of danger And then looking back, saw the water of a cistern, near which they had been at work, spout out to a great height. This was succeeded by a large discharge of fiery matter from the mouth of the cistern, and from four other openings, attended with a dreadful noise and explosion of burning stones. On a sudden all the fiery streams united in one, flowed impetuously down the mountain, and gliding quick as lightning, presently covered all the adjacent lands. Meantime the whole mountain shook greatly, and a fixed pillar of smoke issued out of the main aperture, which rising to a certain height, then dissolved into ashes, and fell like rain all over the mountain. At the same time an immense quantity of burning stones was thrown out.

The fiery stream continues running down the mountain, the whole night between the 23d and 24th. Houses, gardens, and every thing in its way, were consumed. And ashes were still thrown out, which lay deep on the ground for several miles about, and reached as far as the sea coast.

On the 25th, also, there was an eruption of liquid lire, with a shower of stones and a huge noise. In several parts this stream was fifty spans deep. The mountain meantime continued to roar, and thick ashes fell like rain over the whole country.

On the 26th, both the mountain itself and the hills lately produced, sent forth stones and ashes, the bellowings were still heard, but with intermissions : and out of the five apertures, two only continued to emit stones, ashes, and fire.

On the 27th, only one fiery stream remained, and that began to cool, and to lose its brightness, appearing more dusky, like burning coals ready to go. out. On the 28th, the stream ran much slower, and no more burning stones were cast out. The height of the chief hill raised thereby was about two hundred spans; and its circumference about two hundred paces, The motion of the lava in front was very slow; it gained ground only on the sides. The hill where the last aperture was, burst, and fire issued from all the fissures.

On the 29th, the lava having ceased, appeared to have reached about one mile in breadth, and four miles in length The new raised bills were now quiet; but the top of Vesivius still cast out ashes and smoke, and some showers of stones. About eight at night the bill was overturned with a great crack, and on the 30th emitted nothing. But from the mouth of Vesuvius, clouds and ashes came in great abundance. From the whole it appears, that the inflammatory contents take fire at a great depth in the cavern, and it is highly probable, it is the sea water which feeds this subterraneous fire, by means of some communications which the volcano has with the Mediterranean.

Although the fiery eruptions of Mount Vesuvius strike the neighbourhood with horror; yet as even noxious things bring some advantage with them, so this mountain, by the sulphureous and nitrous particles with which it manures the ground, and the heat of its subterraneous passages, much contributes to its common fertility. And wherever these inflammable substances abound, it is better they should have avent than not. So experience shows, that their country has had fewer earthquakes, and those less fatal in their effects, since the eruption of the subterraneous matter, through the mouth of Vesuvius. And the inhabitants are not much alarmed at seeing the usual vernal explosions. ‘

The distance from Naples to the foot of Vesuvius, is five Italian miles, from whence to the top is near three miles further. It properly consists of two hills, though only one of them emits fire and smoke. The valley between them is about a mile long, and extremely fertile. The burning summit, which is the lowest of the two, is eleven hundred fathom above the surface of the sea. From Resina, the ascent grows steeper, and many stones are scattered about as memorials of its former devastations. It is astonishing to think of the force, by which such bulks of four or five hundred weight have been thrown several miles from the hill.

This being steep, and covered with black ashes, the ascent is very difficult. From the mouth frequently issues a flood of lava, or composition of sulphur, metals, and minerals. This ejected matter lies still, one layer above another, with large stones projecting above the surface, which in their course along the fiery river, were stopped by their inequalities, and fixed in the melted matter, gradually hardened. These streams are not thrown up from the mountain,, like the stones, but pour down as from an inclined vessel, proceeding, it seems, from the whole cavity, which is then full of melted substances.

About half way up the mountain, says Mr. Keysber, we met with stones of above a hundred weight, glowing hot, which when broken had exactly the appearance of red hot iron. As we went on, we beard a most horrid noise, resembling the discharge of a whole battery of cannon, and under our feet we perceived a rumbling, like the boiling of a large caldron. At last we reached the place where the largest volcano was formerly mated. But it is now not only choaked up, but covered with a round pile of ashes and lava. Thirty years since there was a plain about three thousand yards to cross, before you came to the skirts of this new mountain. But it is now so enlarged, that in most places, the plain is but about thirty yards broad. Probably in a few years it will be quite filled up, and the two mountains joined in one. Here the increase of heat was very sensible, especially at every explosion, when the ashes flew so strongly in our faces, that we were obliged to cover our eyes. The ground also was so hot under our feet that it burnt the soles of our shoes. Every eruption was attended with a whizzing noise, like that of many rockets thrown up at once. The clouds of smoke, and the multitude of stones thrown into the air, totally obscured the sky. Most of the stones, especially if large, fell again into the abyss from which they were projected. Great quantities however fell on the sides of the mountain, and rolled down with a hideous noise.

Even when all is still, the bottom of the cavity is seldom seen, by reason of the smoke. When it is, it is subject to great variation. Sometimes it is of a prodigious depth: at other times hardly more than a hundred feet, according to the rising or falling of the melted matter, since the last eruption, by the hardening of which this bottom is formed.

Since the birth of Christ, there are recorded upwards of twenty memorable eruptions of Vesuvius. One of the most violent was, that which happened in the reign of Titus Vespasian, and destroyed the cities Herculaneum, Stabice and Pompeii, which then stood near Naples. During that eruption the ashes were driven as far as Africa, Syria and Egypt, and even at Rome, the sun was darkened by them. These cities were partly swallowed up, partly buried in the burning lava, so that not the least remains of them were to be seen.

But within a few years many things have been dug out of Hercularieum, near Portici, the king of Naples’ palace. Among these are many paintings done in stucco, in water colours in fresco. They have been taken from the walls of an amphitheatre, a temple, and several houses, and are in great variety, some perfectly well preserved.

Four capital pieces are so extremely well executed that Don Francesco de la Vega, a painter, whom the king of Naples sent for from Rome, to take draughts of these paintings, said, "if Raphael were alive, he would be glad to study these drawings, and perhaps take lessons from them.” Nothing can be more just and correct. The muscles are exactly and softly drawn, every one in its own place, without any of that preternatural swelling seen in the works of some of the best Italitan masters. And it is surprising to see how fresh the colours are, considering they have been under the ground above sixteen hundred and fifty years.

The matter thrown out at Vesuvius, shows whence its fiery eruptions arise. For, pour water on sulphur, mixed with filings of iron, and it soon breaks out into a dame. That abundance of sulphur and iron is contained in Vesuvius, appears not only from what is ejected, but also from the mineral water, issuing from the foot of the mountain. The neighbouring sea both supplies moisture to these inflammable substances, as also salt and bitumen. That Vesuvius has a communication with the sea, experience shows, the waters being surprisingly absorbed, in 1681, before the eruption, so that several vessels before afloat were left dry. Likewise. in 1698, the sea suddenly ebbed twelve paces and the mountain discharged a torrent of bituminious matter. When the discharge ceased, and the sea returned to its former height, great quantities of shells, half burnt, and emitting a sulphurous smell, were found along the shore In another violent eruption, not only shells, but sea weeds, and hot sea water were ejected.

This volcano, however, affords several fresh springs, some of which are conveyed to Naples, by a beautiful aqueduct. These waters have not the least heat in them. Nay, a cold wind is felt to blow from several fissures and chasms of the mountain.

The whole country for twenty miles or more round Naples, is the product of subterraneous fires. Probably the sea reached the mountains that lie behind Capua and Caserta. These tires seem to have worked under the bottom of the sea, as moles in a field, throwing up here and there a hillock. And the matter thrown out of some of these hillocks formed into settled volcanos, tilling up the space between them, has composed this part of the continent, and many of the islands adjoining.

Were the matter carefully examined, it would be found, (just contrary to the common opinion) that most mountains which are or have been volcanos, owe their existence to subterraneous fire.*

* If we seriously consider the structure of our globe, and reflect on the capacities of the materials of which it is composed, we shall be very apt to discover, that it is not more wonderful that there should be seas, and torrents of liquid fire, than that there should be oceans of water, and tracts of land; that it is not more wonderful, that there should be streams of liquid fire in the bowels of the earth, than that there should be streams of liquid fire in the regions of the air. We should find equal cause of admiration in contemplating the process of the combustion of

It cannot be denied that Herculaneum and Pompeii once stood above the ground, though now the latter is buryed ten or twelve feet deep; the former in no part less than seventy, in some parts a hun

fuel; in the inflammation of a stream of hydrogen gass; in the lava of the skies that streams in fiery meteors to the earth; or in the torrents of liquid fire that belch forth from the yawning mouth of a volcano. The globe of our earth consists of certain proportions of elementary matter, and proportion of the proper constituent elements, forms atmospheric air; a due pro portion of other elements form water, a due proportion of others fire; and certain ratios of various elements, constitue the various earths, &c. and these elements are so proportioned, that they shall be a check upon each other, so that one shall not exceed its proper limits of action. And it is so ordained by the wisdom of the Creator, that those portions of compound matter, which are indispensable, and essential to the production, support, and nourishment of life, more especially abound at the surface of the earth: and those which are inimical, and destructive, are removed to remoter regions. Thus air, earth, and water are more immediately essential, and conducive to the existence of animals, arid vegetables; therefore their situations are assigned to reciprocal convenience. Fire is a: secondary convenience to man, its elements therefore are made to consist in a dormant state, at his disposal, and discretion. But the great laboratories of spontaneous fire are removed to a distance from his habitation; locked up in the deep caverns of the earth, or suspended aloft in the regions of the air, and bound in chains of adamant, that they should not disturb the intermediate habitable region. But sometimes the accumulations of their volumes are so great, as to burst the bolts of their imprisonment, and shoot in spouting columns to the skies, or descend in flaming balls to the earth.

The elements of fire may be more abundantly concentred in one district of the globe than another, those districts therefore will be more subject to its concomitant phenomena. This appears to be the case about the mid-districts of the Mediterranean, in the neighbourhood of Aetna, and Vesuvius, its two awful and memorable mouths; about the coast of Japan; in the districts of the Andes and Cordileres, of South America; about the sold regions of Iceland; and in the sultry region of Gadaloupe, &c. where fiery eruptions, and earthquakes more frequently occur. But no part of the globe is exempt from its destructive inroads, and sometimes it bursts forth in new district,, without any previous warning, laying waste the habitations of man, involving vegetables and animals in promiscuous ruins; alternately heaping up, and levelling huge mountains; presenting new boundaries to the ocean, converting beautiful countries into inhospitable worlds; raising up new islands in the seas; reducing old ones to their bottom; breaking up old continents; and in short, giving a new aspect to nature, like a new creation burying in one fatal moment whole ages of human industry. Such are the dreadful consequences of these tremendous cataracts of fire: but the directions of such mighty revolutions are in the hands of that God who created all worlds, and who alone can controul the raging elements.

The number of volcanos is very great: there are reported considerably more than one hundred. In Eurone there ire, Aetna, Vesuvius, Hecle, Strornboli, Vulcano; in Asia, one in Mount Tarus, three in Kamtschat Ira, five in Japan, two in the Philippines, and a great number more scattered through the islands in the Sooth sea; in Africa, one in Fez, one in the island of Bourbon, one in Fuego, one of the Cape de Verd Islands; and in America, several in the Andes, Morno Garou in St. Vincent, two in Gaudaloupe, in the West Indies, and two discovered by Capt. Cook on the West Coast of North America. These are those of most note.

dred and twelve. As these were buryed by an eruption of Vesuvius, A. D. 79, it must, be allowed, that whatever matter lies between them and the surface of the earth over them, must have been produced since this time.

Pompeii, being farther off, felt the effects of a single eruption only. It is covered with white pumice stones, mixed with fragments of lava and burnt matter. Over this there is a stratum of good mould, about two feet thick. The shower of pumice stones covered also the town Stabiae, with a tract of country thirty miles in circumference. It is observable, the pavement of the streets of Pompeii is of lava: nay under the foundation of the town, there is a deep stratum of lava and burnt matter: hence it is clear, there have been eruptions before that of 79, the first which is recorded in history.

The matter which covers Herculaneum is not the produce of one eruption only. From the strata of mould intermixed, it appears, that five or six eruptions have taken their course over that which lies immediately above the town, with which tile theatre, and most of the houses tire filled. This is not vitrified lava, but a sort of soft stone, composed of pumice, ashes, and burnt matter, It is of the same nature with what the Italians call tufa, and is in general use for building, and is met with only in those countries that have been subject to subterraneous fires. As water frequently attends eruptions of fire, doubtless the first matter that issued from Vesuvius, and covered Herculaneum, was in a state of liquid mud.

Braccini descended into the crater (or hollow on the top) of Vesuvius, a, little before the eruption in 1631. He observes, it was then five miles in circumference, and about 1000 paces deep. Its sides were covered with brush-wood, and at the bottom there was a plain on which cattle grazed, and in the midst of this plain was a narrow passage, through which by a winding path he descended among rocks and stones into a more spacious plain, covered with ashes. In this were three little pools, one of hot water, bitter and corrosive beyond measure; another of water saltier than that of the sea ; the third hot, but tasteless.

The great increase of the cone of Vesuvius, from that time to this, naturally induces one to think, that the whole cone was raised in like manner, as was also that part of it now called Somma. It seems, that this was what the ancients termed Vesuvius, and that the conical mountain, at present called by that name, lies been raised by the succeeding eruptions.

From repeated observations, it appears, that all the soil in the neighbourhood of Vesuvius, is composed of different strata of erupted matter, to a great depth below the level of the sea. And undoubtedly this volcano took its rise from the bottom of the sea.

The soil from Capreae to Naples is of the same sort. And that on which Naples stands, has been evidently produced by explosions, some of them on the very spot whereon the city is built. All the high grounds round it, with the islands of Prochyta and Ischia, appear likewise to have been raised in the same manner.

Such wonderful operations of nature, are certainly intended for some great purpose. They are not confined to one country; volcanos exist in the four quarters of the globe. We see the fertility of the soil occasioned thereby, in what was thence called Campania Felix. The same is evident in Sicily, justly esteemed one of the most fertile spots in the world. May not subterraneous fire be considered as the great plough (if we may be allowed the expression) which nature makes use of to turn up the bowels of the earth, and afford us fresh fields to work upon, when the former are exhausted Perhaps, likewise, many precious minerals might have remained unknown to us, had it not been for these operations of nature.

There is great reason to believe that the whole island of Madeira was at some remote period thrown up by the explosion of subterraneous lire, as every stone, whether whole or in fragments, that is seen upon it, appears to have been burnt; and even the sand itself to be nothing more than ashes. And it is certain, that part of the country near the sea is a very exact specimen of the rest.

7. Near Puzzuolo lies Monte Secco, which is Vesuvius in miniature. Its summit, formerly a cone, is now sunk into a concave oval, whose shortest diameter is about one thousand feet. the longest, one thousand two hundred and forty-six. It is generally known by the name of Solfatara. Though Vesuvius is twelve miles distant, yet they have a communication with each other. Hence the subterraneous fire is quiet at Solfatara, when it has a vent at Vesuvius : whereas the heat at the former increases, when the latter is at rest.

On this mountain are many cracks emitting smoke; the heat issuing from them is sometimes insupportable. Hold a piece of iron over one of these cracks, and a sweetish fluid will drop from it: but a piece of paper, instead of being moistened, grows quite dry and still. The stones near these cracks are in continual motion ; and small stones dropped into them are ejected to the height of twelve feet, like the ponderous masses from Vesuvius. In some places the sand, by the force of the vapours, springs up and down like the sparkling of cider.

Out of Solfatara they extract besides sulphur, blue vitriol, and the best kind of alum. The large leaden kettles used therein, are not heated by a culinary fire, but by the natural heat, issuing through holes in the ground, over which the vessels are placed,

8.Not far from Puzzuolo is Monte Nuovo, which rose suddenly in the night, between the 19th and 20th of September, 1636. During a dreadful earthquake, that laid the whole neighbourhood in ‘ruins, the subterraneous fire opening a large chasm in the ground, threw out such quantities of stones, ashes, bitumen and sand, as in twenty-four hours formed this mountain. Its perpendicular height is 400 rods, its circuit three miles. The edge of the first aperture is still visible, a mile in circuit, though it is now entirely filled up.

9.An event similar to this occurred more lately. After a shock of the earth, there was seen from Santorini, (an island in the Archipelago, on the coast of Natolia) on the 23d of May, 1707, as it were a floating rock. Some were so bold, as to go down upon it, even while it was rising under their feet. The earth of it was very light, and contained a small quantity of potter’s clay. It increased daily, till it was half a mile in circumference, and twenty or twentyfive feet high. ,At this time a great ridge of rocks, dark and black, rose out of the sea, and joined to the new island. Then there issued out of it a thick smoke, with a noise like constant thundering, or a discharge of many cannon at once. The sea water continually bubbled up; and in a short time the new land presented nothing to view for whole nights, but a great number of stoves, which cast forth flames, with showers of ashes, and innumerable small stones, red hot. Rocks were also darted out of these burning furnaces, which mounted up like bombs. This continued till November.

There is likewise an island among the Azores, which had the game originial. On the night between the 7th and 8th of December, 1720 there was felt a shock of an earthquake at Tercera: and, presently after an island rose, from the midst of boiling hot water. it was nearly round, and high enough to be seen seven or eight leagues off. But after a little while it sunk, till it became level with the water.

10. On June 4th, 1693, the mountain on the island Torca, in the East Indies, began about daybreak to cast out more fire than usual, which continued five or six days., till at last it poured forth, not only a prodigious name, but likewise such a black and sulphurous vapour, that the inhabitants of Hislo (a village in the western part of the island, and nearest to the opening) were wholly covered by it. Quickly followed a stream of burning brimstone, which consumed many that could not escape. Afterwards the inhabitants perceived a great part of the mountain was sunk down. Another part sunk three or four days after, and so from time to time, till the burning lake covered near half the island. Wherefore they went on board their boats : from whence they perceived huge. pieces of the mountain fill into the fiery lake, with a prodigious noise, as if a whole battery of cannon was discharged. The inhabitants of another town on the east side of the island, not thinking themselves in so great danger, remained a month longer. But the fiery lake approaching nearer and nearer, so that there was no doubt but it would swallow up the whole island, they too fled for their lives, and arrived at Amboyna, July the 18th, 1693 .

In the mountains of Ternata, a terrible noise is continually heard. The fire frequently casts out stones, and lies exceeding deep. Probably the burning mountains in the Molucca islands are consumed beneath by the same fire. Manilla is one of the largest of the Phillippine islands. The city is much larger than Oxford, is an university, and is inhabited only by Spaniards. The houses are large, and built very strong. The lower walls are stone, and of a prodigious thickness. All above is wood, and every piece of timber has a connexion with the others, and all are joined together, that the earthquakes, which are very frequent, may not throw them down. In 1750, they had an earthquake with almost continual tremblings for three months., Then followed an eruption in a small island, surrounded by a large lake, which is unfathomable. The third day after the eruption began, there arose in the lake four more small islands, all burning. About a mile from one of these, there is a fire rising continually of the water, in a part where there is no ground for above a hundred fathoms.

11. A particular account of a journey to Mount Hecla, is given by a late author. We travelled, says he, two days in rugged and unfrequented roads. Then we came within six miles of the mountain, and perceived the ground strewed with ashes and pumice stone, over which we passed to the foot of it. The weather being serene and calm, and no flames issuing out of the volcano, we resolved to get to the top; till being informed by our guides, that if we went any further we should be in danger of falling into pits, where we might be suffocated by the fumes rising Out of the earth, all my company declined it. I told them, if they would stay for me, I would go alone. They promised they would. So I alighted and prepared to go up, when one of them offered to go up with me.

Having given our horses to our guides, who stayed with the rest of our company, we ventured forward, resolving to reach the top, and in a short time saw a large flight of crows and vultures, that had their nests in the top of the mountain. Having ascended about half a league, we felt the ground shake under us, and heard a terrible noise in the bowels of the earth, just as if it were going to burst open. At the same time there appeared on all sides chinks, out of which issued bluish flames, with a strong suffocating smell. This made us turn back, for fear of’ being burnt to ashes. But we had scarce proceeded thirty yards back, before a black cloud of smoke ascended out of the mountain, obscured the light of the sun, and covered us so thick, that we could not see. each ether. Our fears increased every step we took: for behind us name flames of fire, with showers of ashes and pumice stones, which fell’ as thick as hail. This dreadful storm was attended with horrible noises, and we expected every moment, that earth would open and swallow us up. This added wings to our flight, so that in a quarter of an hour we got to the bottom of the mountain.

There are volcanos likewise in many of the American islands: and a very eminent one in Gaudaloupe. The summit of this constantly emits smoke, and sometimes flames. It rises very high, in the form of a cone, above the chain of mountains that occupy the centre of the island. Near ‘the foot of it there are springs, the water of which are so hot as to boil eggs in three minutes. The neighbouring ground smokes, and is full of brown earth like the dross of iron. But he chief place where the smoke issues out, is higher up at the foot of a steep bank, about fifty yards in breadth. Here no grass is to be seen; ‘nothing but sulphur and calcined earth. The ground is full of deep cracks, which emit much smoke, and where you may hear the sulphur boil. But the stench of it is intolerable. The ground is loose,’ so that you may thrust a cane up to the head. And when you draw it up, it will be as hot as if you had plunged it into slacking lime.

On the plain top of the hill is another funnel, that opened some years since, and emits nothing but smoke. Here are abundance of large and deep chinks, which doubtless burned in former times. In the middle of this plain is a very deep abyss. It is said there was Once, a great earthquake in the island, and that the Brimstone Hill (so they call it)’ then took tire. It was probably then this abyss was opened. It is between two crags that rise above the mountain, and on the north side answers to the great cleft, which goes down above a thousand feet perpendicular, is more than twenty feet broad, and penetrates above a hundred paces in the flat. So that in this place the mountain is fairly split, from the top down to the basis of the cone.

On this plain you may see the clouds gather below, and hear the thunder rumble under your feet. The great cavern is under the cleft, and was doubtless formed by the same earthquake that split the mountain in two parts nearly equal. The parting goes north and south. To the north is the cleft and cavern, in the middle the abyss. and to the south the burning gulph, The cavern is about twenty-five feet wide, as much in height, and about sixty paces deep. Within this is a second cave, about sixty feet in length, as much in breadth, and forty in height. Here the heat is moderate: but there is a third cave within this, where it is so hot, that a torch will give no light therein, and a man can scarce fetch breath. Yet on the left is a great. hollow, which is sufficiently cool. And the space of one fathom makes the difference. It seems strange, that in the same cave, three hundred feet under ground it should be so hot on one side, and so cool on the other. Perhaps the cool side has some vent into the great cleft, and receives fresh air thereby. ‘

13. Another surprising eminence, which may be ranked among burning mountains, is the Peak of Teneriffe. On the summit of it is a hollow, twelve or fourteen feet deep: the sides sloping down to the bottom, form a cavity like a truncated cone, with its base uppermost. This cavity is nearly circular, about forty fathoms across. The ground is very hot, and from nearly twenty vents, issues a smoke of a strong sulphurous smell. The whole soil seems powered with brimstone, which forms a beautifully coloured surface. Almost all the stones thereabouts are of a greenish colour, sparkling with yellow. like gold. On the middle of one of the rocks is. a hole, about two inches in diamater. Hence proceeds a noise like that of a great body’ of liquors boiling very strongly. And so hot a steam comes from it, as will burn the hand, even at a quarter of a yard’s distance.

A small part of the sugar-loaf is white like lime; another small part is covered with salt. But the far greatest part is covered with snow, almost throughout the year.

The accounts given of its height are exceeding various. But a gentleman some years ago, who measured it exactly, found a perpendicular height to be two thousand five hundred and sixty-six fathoms.

14. When it happens that any inflammable substance takes fire in the caverns of the earth, the air contained therein is rarefied and exploded with an immense force. Hereby not only the arch which covers it, but the whole body of incumbent earth is shaken. And this is one species of earthquakes. In this case, the deeper the cavern is, and the larger the quantity of matter which takes tire, the more extensive and the more violent the earthquake. If the cavern is near the surface of the earth, the tire often issues out of it: and the lower parts being eaten away, the ground sinks in, and swallows up houses or whole cities.

But, to consider this point a little more minutely. As some earthquakes are owing to tire, so are some to air, others to water, and others to earth itself. 1. The earth itself may be the occasion of its own shaking, when the root or basis of some large mass being worn away, the mass sinks in by its own weight, and causes a concussion of all the neighbouring parts. 2. Subterraneous waters wash way the foundations of hills, and eat far under the earth. By this means many earthquakes have been occasioned, and whole cities swallowed up. This was undoubtedly the cause of the great earthquake at Port Royal, and of that which swallowed up Lima. 3. Air pent up in the bowels of the earth, if it be at any time rarefied and expanded will struggle for vent with incredible force, and thereby and tear the earth. 4. But the usual cause of the most violent earthquakes, is sulphur, or some other inflammable matter taking fire in the cavities of the earth, and bursting through whatever

There are scarce any countries that are much subject to earthquakes, which have not some burning mountain. And whenever any earthquake happens, this is constantly in flames. Indeed were it nut that these vents thus disgorge the fire, it would make far greater havoc than it does ; probably it would make the whole country for a vast space round quite uninhabitable. Yea, so beneficial are these, that we do not want instances of countries frequently annoyed by earthquakes, winch, upon the breaking out of a volcano, bare been wholly delivered them.

Perhaps what causes most earthquakes of this kind, is the pyrites, or iron stone, which will take fire of itself. The earth, we know, in cavities, which are at certain times full of inflammable vapours. This the damps in mines show, which being fired, do every thing as in an earthquake, only in a less degree. And the pyrites only, of all known minerals, yields this inflammable vapour. Nor is any mineral or ore, however sulphurous, but what is more or less mixed with the pyrites. But probably the pyrites of the burning mountains, is more sulphurous than ours. It is likewise in far greater quantities in all the countries round the Mediterranean than in England: a plain reason why earthquakes are so much more frequent and more violent there. All artificial earthquake may be made thus: add twenty pounds of twenty of iron filings; mix and temper these with water, so as to form a mass of the consistence of a firm paste bury this three or four feet under ground. In six or seven hours time, the earth will bean to tremble, crack and smoke, and fire and flame will burst through. So that there only wants a sufficient quantity of this matter to produce a true Aetna. lf it were supposed to burst out under the ads, it might occasion a new island.

To explain this point a little farther. This globe of earth is bored through with infinite cavities, which branching out like the veins, arteries and nerves, in our bodies, pass under the very bottom of the some of them serve to convey water, others a more unctuous substance, others an ingenious matter, that gives motion to the whole frame.

Thus the exterior sea communicates with the inmost abyss, and passes to the roots of the hills and mountains. Mean time a constant air or wind, forces the water into the dark caverns, and receives and keeps alive a perpetual fire.

Have we not indubitable examples of these things Does not the vast river Wolga, pour such a quantity of water into the Caspian within the space of one year, as would be sufficient, were there not some invisible outlet, to cover the whole earth. This invisible outlet is a huge cavern that passes under Mount Caucasus into the Euxine Sea. Hereby the waters of the one sea, discharge themselves into the other. And the whole kingdoms of Georgia and Mengrelia, are as it were •a bridge over those subterraneous waters.

When the Caspian Sea has been, on occasion of winds, too much emptied into the Euxine, it is. replenished from the Persian Gulf, which is a kind of reservoir for it. And the subterraneous communication between the Red Sea and the Mediterranean, is now out of all dispute.

And how many instances of this have we in rivers So late geographers assure us, that the river Niger in Africa is derived from the river Nile, under the mighty chain of mountains of Nubia; on the western side of which mountains, it takes the name of Niger, and continues its course into the Atlantic ocean. So the vast and deep cave in Mount Taurus, receives the Tigris, and gives it a passage to the other side. The same river afterward hides itself under the ground, for near twelve miles, and then breaking out again, disembodies into the Euphrates, near Babylon.

To come nearer home ; the Guardiana, that runs between Spain and Portugal, runs thirty-two miles under ground. Yea, in our own country, the Mole in Surry, falls into the ground near Boxhill, and rises again at a considerable distance.

Hence we may safely collect, that the earth is filled with subterraneous aqueducts and caverns, full of air and vapour, and copious exhalations from aal sorts of minerals, as well as water.

Besides these cavities, there are mountains whose bowels are in a continual flame. And their belching out ashes, smoke, broken rocks and minerals, argues vast vacuities, and huge magazines of combustible matter which are lodged therein. In the chain of mountains called the Andes in America, there are no less than fifteen volcanos, ‘by whose burnings, caverns as big as whole kingdoms are made, and receive the cataracts of mighty rivers. And not only here, but over all the earth there are so many channels, clefts, and caverns, that we do not know when or where we stand upon good ground. Indeed it might amaze men of a stout heart, could they see into the world beneath their feet, view the dark recesses of nature, and observe the strongest buildings stand upon art immense vault, at the bottom of which runs an unfathomable sea, and whose upper hollows are filled with stagnating air, and the expirations of sulphurous and bituminous matter.

Therefore, as there are no large tracts of land without volcanos and sulphurous caverns; from which branching into smaller pipes, the subterraneous heat is conveyed throughout the earth: so no country promise itself an entire immunity from earthquakes: even were there no other cause of these dreadful events, but subterraneous. Especially, when it is considered, that the earth is in one part impregnated with sulphur, in others with nitre, alum, vitriol, mercury, bitumen, ochre, and chalks. For if an artificial powder, made only of nitre, sulphur, and charcoal, has so wonderful affects, what force must that combustible matter have, which arises from sulphur, nitre, salammoniac, bitumen, gold, copper, iron, arsenic, mercury, and other metallic and mineral spirits, with which the womb of the earth abounds’, when the subterraneous fires break through into the hollow vaults, where these are reposited by the Cod of nature Then, according to the copiousness of these combustibles, and the more or less firmness of the superincumbent earth, these fires cause tremblings and concussions, or violent eruptions : and perhaps open wide and. deep gulfs wherein whole cities, yea, mountains are swallowed up.

*Many ingenious hypotheses have been framed, and alternately advocated and rejected respecting the cause of earthquakes. Anaxagoras ascribed it to the bursting of subterraneous clouds. which shook the vaults which confined them. Some have ascribed it to vacuums occasioned by the instantaneous decomposition of volumes of subterraneous gasses; others, to the rarefied steam of aqueous matter, heated by contiguous fires: while others have attributed it, with more apparent plausibility, to inflammable exhalations. This hypothesis has been adopted by some of the more modem and most celebrated philosophers, among whom we find recorded the names of Gassendus, Kercher, Schottos, Varenius Des Cartes, Du Hamel, Honorius, Fabri, &c. the last of whom, indeed, sup. posed that water prodigiously rarefied by heat, might sometimes occasion earth quakes: the others supposed there were many cavities within the earth, communicating and charged with different vapours, originating from their various contents; as water, nitre, bitumen, sulphur, &c. The latter doctrine appeared to be confirmed by various experiments, such as mixtures of iron filings and brimstone, and gunpowder, confined in pits, &c. But these inferences were from too superficial considerations. The authors and advocates of the doctrine did not take into the general review the incontestable fact, that these explosions merely had relation to the degrees of resistance of the superincumbent medium in which they occurred: they did not recollect at the time, that these explosions could not take place in vacuo, that they could not take place in a degree of rarefication equal to the power of expansion, and that the violence of the explosion, depended on the degree of resistance of the opposing medium; otherwise, the reflections would have led them on in a regular train, to develope more obvious causes.

These several hypotheses were at length abandoned, to make room for another, of still more apparent plausibility, it was derived from a consideration of the progressive gradations of density, from the surface towards the centre of the earth, and according to the philosophical principles, which supposes the atmosphere to be about 45 miles in height, and that the density of the air increases, in proportion to the absolute height of the superincumbent column of fluid: whence it is shown, that the depth of 43,528 fathoms below the surface of the earth, the air is but One fourth lighter than mercury: and this depth being only a 74th part

Many such instances occur in history. Pliny tells us, that in his own time, the mountain Cymbotus, with the town of Eurites, which stood on its side, were totally swallowed up. He records the like of the city of Tantelis in Magnesia, and after it, of the mountain Sopelus, both absorbed by a violent opening of the earth, so that no trace of either remained. Galanis and Garnatus, towns once famous in Phoenicia, are recorded to have met the same fate. Yea, the vast promontory, called Phelegium, in Ethiopia, after a violent earthquake in the night, was not to be seen in the morning, the earth having swallowed it up and turned over it.

Some instances we have of later date. The mountain Picus, in one of the Moiuccas, was so high that it appeared at a vast distance, and served as a landmark to sailors. But during an earthquake in the isle, the mountain in an instant sunk into the bowels of the earth; and no token of it remained, but a vast lake of water. The like happened in the mountainous parts of China, in 1556: when a whole province, with all its towns, cities, and inhabitants, was absorbed in a moment; an immense lake of water remaining in its place, even to this day.

In the year 1546, during the terrible earthquake in the kingdom of Chili, several whole mountains of the Andes, one after another, were

of the semidiameter of the earth, it would follow, that the air in the vast sphere below this depth, consisting of 6,451,538 fathoms, would become exceedingly condensed, and much heavier than the heaviest bodies we know in nature; and it is found by experiment, that the more air is compressed, the more does the same degree of heat, increase its spring, and the more capable does it render it, of violent effects. The degree of heat of boiling water, in the degree of density at the surface of the earth, increases the spring of the air, by a quantity equal to a third of the weight wherewith it was pressed, and this degree of heat, which would only produce a moderate effect in that degree of density, would be capable of the most violent effects below. It is certain, there are more violent degrees of heat, than that of boiling water, and it is possible, there may be some, whose violence, further increased by the immense weight of air, may be sufficient to break and overturn, this solid orb of 43,528 fathoms, the weight of which, would be but a trifle, to the expanding force of the included air.

This doctrine, however, soon gave way, and yielded to one of a more specious kind, and which substituted electricity as the formidable agent; but this met with a host of objections. .

By pursuing the train of reflections held out in a former paragraph, we should be led to the following conclusion: that all earthquakes are occasioned by an excessive accumulation of voluminous matter, in the bowels of the earth; that could the earth yield to its volume, the phenomena of vibration and explosion, could not take place; that the violence of the shocks, will be in proportion to the degrees of compression, to which the volumes are subjected, or to the degree of resistance opposed to their currents; that should the volumes of matter find a passage longitudinally through the strata of the earth, it would consequently occasion a vibration of its surface; and this we call earthquake, or a tremulous motion of the earth. We should be led to conclude, that the accumulated matter is a compound, whose bulk is increased by union, and that when it is disgorged from its bed, it travels irresistibly, to find a place where it can repose in quiet.

wholly absorbed in the earth. Probably many lakes, of whose beginning we have no account, were occasioned by the like absorbtions.

The greatest earthquake we find in antiquity is that mentioned by Pliny in which twelve cities in Asia Minor were swallowed up in one night But one of those most particularly described in history is that the year 1693. It extended to a circumference of two thousand hundred leagues, chiefly affecting the sea coasts and great rivers. Its motions were so rapid, that those who lay at their length were tossed from side to side as upon a rolling billow. The walls were dashed from their foundations, and no less than fifty-four cities, with an incredible number of villages, were either destroyed or greatly damaged. the city of Catanea, in particular, was utterly overthrown. A travel who was on his way thither, at the distance of some miles perceived a black cloud hanging near the place. The sea all of a sudden began to roam. omit Etna to send forth great spires of flame; and soon after shock ensued, with a noise as if all the artillery m the world had been at once discharged. Our traveller being obliged to alight, instantly felt himself raised a foot from the ground, and turning his eyes to the city, saw nothing but a thick cloud of dust in the air. Although the shock ‘did not continue above three minutes, yet near nineteen thousand of the inhabitants of Sicily perished in the ruins.

The following account of a dreadful earthquake at Calabria, in 1638, is related by the celebrated father Kircher, as it happened while he was on his journey to Mount AEtna.

"Having hired a boat, in company with four more, we launched on the 24th of March, from the harbour of Messina, and arrived the same day at the promontory of Polorus Our destination was for the city of Euphaemia, in Calabria But though we often put to sea, we were as often driven back.’ At length, however, we ventured forward. Proceeding onward, and turning my eyes to Aetna, I saw it cast forth large volumes of smoke, which entirely covered the whole island. This, together with the dreadful noise, tilled me with apprehension.. The sea itself began to wear a very unusual appearance, covered all over with bubbles. My surprise was increased by the calmness of the weather. I therefore warned my companions that an earthquake was approaching, and making for the shore with all possible speed, we landed at Tropae. But we had scarce arrived at the Jesuit’s college, in that city, when our ears were stunned with a horrid sound, resembling that of an infinite number of chariots driven fiercely forward, the wheels rattling and the thongs cracking. Soon after the whole tract upon which we stood, seemed to vibrate, as if we were in the scale ‘of a balance that continued wavering. This soon grew more violent, and being no longer able to keep my legs, I was thrown prostrate upon the ground. In the mean time, the universal ruin round me, redoubled my amazement. The crash of falling houses, the tottering of towers, and the groans of the dying, all contributed to raise my terror. On every side of me I saw nothing but a scene of ruin, danger threatening wherever I could fly. I recommended myself to God as my last refuge. At that hour, 0 how vain was every sublunary happiness! Wealth, honour, empire, wisdom, all mere useless sounds, and as empty as the bubbles on the deep. Just standing on the threshold of eternity, nothing but God was my pleasure, and the nearer I approached, I only loved him the more. After some time, however, I resolved to venture for safety, and running as fast as I could, reached the shore. I did not search long, till I found the boat in which I had landed my companions also. Our meeting was all silence, and gloomy dread of impending terrors.

Leaving this seat of desolation, we prosecuted our voyage, and the next day landed at Rochetta, although the earth still continued in violent agitations. But we were scarce arrived at our inn, when we were obliged to return to the boat, and in about a half an hour, we saw the greatest part of the town, and the inn at which we had put up, dashed to the ground, and burying all its inhabitants beneath its ruins. Proceeding onward in our little vessel, finding no safety at land, and yet having but a very dangerous continuance at sea, we at length landed at Lipizium, a castle midway between Trapae and Euphaemia. Here, wherever I turned my eyes, nothing but scenes of ruin and horror appeared; towns and castles levelled to the ground Strombalo, though at sixty miles distance, belching forth flames in an unusual manner. But my attention was quickly turned to nearer danger. The rumbling sound of an earthquake alarmed us. It every moment seemed to grow louder, and to approach more near. The place on which we stood, now began to shake most dreadfully, so that being unable to stand, my companions and I caught hold of the shrubs near us, and supported ourselves in that manner.

After some time this shock ceasing, we stood up in order to go to Euphaemia, that lay within sight. In the mean time, I turned my eyes towards the city, but could see only a dark cloud resting upon the place. This the more surprised us, as the weather was so serene. We waited till the cloud was passed away, then looking for the city, it was totally sunk. Nothing but a putrid lake was seen where it stood. We looked about for some one that could tell us the sad catastrophe, but could see none. All was become a melancholy solitude, a scene of hideous desolation. Such was the fate of the city of Euphaemia, and as we continued our melancholy course along the shore, the whole coast, for the space of two hundred miles, presented nothing but the remains of cities. Proceeding thus along, we at length ended our distressful voyage, by arriving at Naples.

15. Of the great earthquake at Port Royal, in Jamaica, an eye-wit.. ness writes thus. It happened on July 7, 1692, just before noon, and in the sp ace of two minutes, shook down and drowned nine-tenths of the town. The houses sunk outright thirty or forty fathom. The earth opened and swallowed up the people in one street, and threw them up in another; some rose in the middle of the harbour. While houses on one side of a street where swallowed up, those on the other side where thrown on heaps. The sand in the street rising like waves in the sea, lifted up every one that stood upon it. Then suddenly sinking into pits, the water broke out, and rolled them over and over. Sloops and ships in the harbour were overset and lost; the Swan frigate was driven over the tops of many houses. All this was attended with a hollow rumbling noise. In less than a minute, three quarters of the houses, with their inhabitants, were all sunk under water: and the little part which remained was no better than a heap of rubbish. The shock threw people down on their knees, or their faces, as they ran about to look for shelter. Several houses, which were left standing, were removed some yards out of their places. One whole street was made twice as broad as before. In many places the earth cracked, opened and shut, with a motion quick and fast. And two or three hundred of these openings might be seen at a time. In some of these people were swallowed up, in others caught by the middle and pressed to death. In others the heads of men only appeared, in which condition dogs came and ate them. Out of some of these openings, whole rivers of water spouted up a prodigious height: and out of all the wells the water flew, with a surprising violence The whole was attended with a noisome stench, and the noise of falling mountains at a distance, while the sky in a minute’s time turned dull and reddish, like a glowing oven. And yet more houses were left standing at Port Royal, than in all the island beside. Scarce a planter’s house or sugar work was lea throughout all Jamaica. A great part of them was swallowed up, frequently houses, People and trees at one gap, in the room of which there afterward appeared a large pool of water. This, when dried up, discovered nothing but sand, without any mark that house or tree had been there. Two thousand people lost their lives: bad it been in the night, few would have escaped. A thousand acres of land were sunk: one plantation was removed half a mile from its place. Yet the shocks were most violent among the mountains. Not far from Yallhouse, part of a mountain, after it had made several leaps, overwhelmed a whole family, and great part of a plantation, though a mile distant. A large mountain, near Port Morant, about a day’s journey over, was quite swallowed up, and in the place where it stood, remained a lake, four or five leagues over. Vast pieces of mountains, with all the trees thereon, falling together in a confused manner. stopped up most of the rivers, tilt swelling abroad, they made themselves new channels, tearing up every thing that opposed their passage, carrying with them, into the sea, such prodigious quantities of timber that they seemed like moving islands. In Liquania, the sea retiring from the land, left the ground dry for two or three hundred yards. But it re turned in a minute or two, and overflowed a great part of the shore. Those who escaped from the town, got on board the ships in the harbour, where many continued two months : the shocks all the time being so violent that they durst not come on shore. The noisome vapours occasioned a general sickness, which swept away three thousand of those that were left.

The following account of this memorable event is given by the rector of Port Royal.

On Wednesday, June 7, I had been reading prayers, (which I have read every day since I came to Port Royal, to keep up some show of religion amongst the most ungodly people) am] was gone to the president of the counsel. We had scarce dined, when I felt the ground heave and roll under me. I said, Sir, what is this “ He replied composedly, It is an earthquake. Be not afraid ; it will soon be over.” But it increased more and more : and presently we heard the church and the tower fall. Upon this we ran to save ourselves; I quickly lost him and run towards Morgan’s Fort: as that was a wide open place. and secure from the falling of houses. As I ran, I saw the earth open, and swallow up multitudes of people, and the sea mounting over the fortifications. I then laid aside all thought of escape, and went homeward to meet death in as good a posture as I could. I was forced to go through two or three narrow streets, the houses fell on each side of me. Some bricks came rolling over my shoes, but none hurt me. When I came to my lodgings, I found all things in the same order that 1 left them. I went to the balcony, and saw that no houses in our street were fallen. The people seeing me, cried to me, to come and pray with them. When I came into the street, every one laid hold of my clothes and embraced me. I desired them to kneel down in a ring, and prayed with them near an hour, till I was almost spent, between the exercises, and the heat of the sun. They then brought me a chair, the earth working all the time, like the rolling of the sea, insomuch, that sometimes while I Was at prayers, I could hardly keep on nay knees. By the time I had been half an hour longer with them, inn setting their sins before them, and exhorting them to repentance, some merchants came, and desired me to go on board one of the ships in the harbour. From the top of some houses, which lay level with the water, I got into a boat, and went on board the Siam Merchant. The day when this happened was exceeding clear, and afforded no suspicion of evil. But about half an hour past eleven, in less than three minutes. Port Royal. one of the fairest towns inn the English plantations, was shattered in pieces, and left a dreadful monument of the justice of God.

About ten years after the town was rebuilt, a terrible fire laid it in ashes. Yet they rebuilt it once more. But in the year 1722, a hurricane reduced it a third time to a heap of rubbish. Warned by these extraordinary calamities, which seemed to mark it out as a devo ted spot, they removed the public offices from thence, and forbade any market to be held there for the future,

16.Lima, in Peru, contains about 60,000 persons, in 1747, an earthquake quake laid three-fourths of the city level with the ground.

17. Calloa, the port of Lima, containing or 4000 inhabitants, was totally destroyed. Only one man escaped, and that by a very singu lar providence. He was going to strike the flag on the fort, that overlooked the harbour, when he saw the sea retire to a considerable distance and then return, swelling mountains high. The inhabitants ran from their houses in the utmost degree of terror and confusion. A cry for mercy arose from all parts: and immediately all was silent, the sea had quite overwhelmed the city, and buryed it for ever in its bosom. But at the same time it drove a little boat to the side of the fort, into which the man leaped and was saved.

18. Perhaps we have not in history, many more remarkable deliverances than of this good man, But more remarkable, if possible, is the following deliverance, from a danger of a very different kind.

In the neighbourhood of Demoate as one descends through the up- valley of Stura, towards the middle of the mountain, there were some houses in a place called Bergemolletto, which on the 19th of March , in the morning (there being then a great deal of snow) were entirely overwhelmed by two vast bodies of snow, that tumbled . town from the upper Alps., All the inhabitants were then in their houses, except one Joseph Rochia, a man of about 50. Two and twenty persons were buried under this mass of snow, which was sixty English. feet in height. Many were ordered to give them assistance; but were not’ able to do them the least service. After five days, Joseph Rochia got upon the snow, (with his son, and two broth. era of his wife) to try if they could find the place under which his house and stable were buried; but they could not, However, the month of April proving very hot, and the snow beginning to melt, this unfortunate man was again encouraged to use his best endeavours, the 24th the snow was greatly diminished, and he conceived of finding out his house by breaking tine ice. He thrust down a long pole, but the evening coming on, he proceeded no farther. His wife's brother dreamed the same night, that his sister was still alive, and begged him to help her. He rose early in the morning, told his dream to Joseph and his neighbours, and went with them to work upon the snow. where they made another opening, which led them to the house they searched for: but finding no dead bodies in its ruins, they sought for the stable, which was about 240 English feet distant, and having found it, they heard a cry of help my dear brother.” Being greatly surprised as well as encouraged by these words, they laboured till they had made a large opening, through which the brother went down, where the sister, with a feeble voice told him, I have always trusted in God and you, that you would not forsake me.” The other brother and the husband then went down, and found still alive the wife about 45, the sister about 35, and a daughter about 13 years of age. These they raised on their shoulders to men above, who pulled them up, and carried them to a neighbouring house; they were unable to walk, and so wasted,. that they appeared like mere shadows.

Some days after the intendant came to see them, and they gave him the account that follows. In the morning of the 19th of March, we were in the stable, with a boy six years old, and a girl about 13. In the same stable were six goats, one of which had brought forth two dead kids the evening before; there were also an ass and five or six fowls. We were sheltering ourselves in a corner of the stable, till the church bell should ring, intending to attend the service. The wife wanting to go out of the stable to kindle a fire for her husband, then clearing away the snow from the top of the house, she perceived a mass of snow breaking down towards the east, on which she went back into the stable, shut the door, and told her sister of it. In less than three minutes they heard the roof break over their heads, and also part of the ceiling of the stable. The sister advised her to get into the rack and manger, which she did very carefully. The ass was tied to the manger, but got loose by struggling; and though it did not break the manger, it threw down the little vessel which the sister took up, and used afterwards to hold the melted snow, which served them for drink. Very happily, the manger was under the main prop of the stable, and thereby resisted the weight of the snow, Their first care was to know what they had to eat: the sister had in her pockets fifteen chesnuts; the children said they had breakfasted, and should want no. more that day. They remembered there were 30 or 40 loaves in a place near the stable, and endeavoured to get at them but were not able, by reason of the snow. On this they called out for help as loudly as they could, but no one heard them. The. sister came again to the manger, after she had tried in vain to get at the loaves, gave two chesnuts to the wife and eat two herself, and they drank some snow water. All this while the ass continued kicking, and the goats bleated very much, but soon after, they heard nothing more of them. Two of the goats however were left alive, and were near the manger; they felt them carefully, and knew by so doing, that one of them was big, and would kid about the middle of April; the other gave milk, wherewith they preserved their lives,

The women affirmed, that during all the time they were buried, they saw not one ray of light; nevertheless, for about twenty days. They had some notion of night and day: for when the fowls crowed, they imagined it was break of day, but at last the fowls died; The second day, being very hungry, they ate all the remaining chesnuts, and drank what milk the goat yielded, which for the first days was near two pounds a day, but the quantity -decreased gradually. The being very hungry, they again endeavoured to get to the place where the loaves were, but they could not penetrate to it. Then resolved to take all possible care to feed the goats, as very fortunately over the ceiling of the stable, and just above the manger, there was a hay-loft with a hole, through which the hay was put down into the rack. This opening was near the sister, who pulled down the hay, and gave it to the goats, as long as she could reach it, which when she could no longer do, the goats climbed upon her shoulders, and reached it themselves. On the sixth day the boy sickened, complaining of violent pains in the stomach for six days, on the last of which, he desired his mother, who all this time had held him in her lap, to lay him at his length in the manger. She did so and taking him by the hand, felt it was very cold: she then put his to her mouth, and finding it likewise very cold, she gave him a little milk; the boy cried, 0 my father in the snow! Oh! father!” and. expired.

The mother told the sister, that the boy was dead, and then laid him in the manger, where the sister was. In the mean while the milk given by the goat diminished daily. The fowls being dead, they could no longer distinguish night and day: but according to their calculation the time was near, when the other goat should kid, which as they- computed would happen about the middle of April. At length they found the goat was kidding by its cries, the sister helped it; they killed the kid to save the milk for their own subsistence. And now they knew it was the middle of April. Whenever they called this goat, it would come and lick their face and hands, and gave them every day two pounds of milk, for which they still bear a great affection to it.

During all this time, hunger gave them but very-little uneasiness, except on the first five or six days. Their greatest pain was from the extreme coldness of the melted snow-water, which fell on them; from the stench of the dead ass,-dead goat, and fowls; but more than all from the uneasy posture they were obliged to continue in. For though the place in which they were buried was twelve English feet long, eight wide, and five -high, the manger in which they sat squatting against the wall, was no more than three feet four inches broad.

19.May we not impute to earthquakes, those huge cavities in the which are found in several parts of England Such is Poole's Hole, about half a mile from Buxton, in Derbyshire, said to have been the refuge of one Poole, a noted robber. It is at the foot. of a mountain; its entrance is low and narrow; but it presently opens into a broad and lofty concavity, of above a mile in length. The water dropping from the roof, congeals into a kind of chrystal, and forms a thou- sand surprising figures. Here is also, a large clear stone, resembling alabaster, which the queen of Scots when here, called her pillar, and it still goes by that name. Along the middle a stream of water falls among the rocks, which loudly echos through the vault. The most striking thing is, the height of the arch, and the spangled roof resembling fret-work. And indeed the drops of water, which petrifying as they fall, form icicles, resembling chrystal above, and pyramids hardened into stone below, have a surprising effect from the light of the candles; the hanging drops dazzling the eyes, as if this mighty arch was covered with diamonds. .

Elders Hole is a frightful chasm in the middle of a field, fifty or sixty feet long, and about twenty broad. But how deep it is, could never be discovered, notwithstanding all the attempts that have been made. Mr. Cotton endeavoured to fathom it with a line of sixteen hundred yards; but in vain. Some suppose these to have been passages, whereby the waters of the deluge returned from the surface of the earth to the great abyss.

There Is another effect of subterraneous fires, which has been generally imputed to quite different causes. The Giant’s Causeway, in Ireland, and all other strong concretions of the same kind, where pillars are formed by pentagon, hexagon, or multangular stones, placed one upon another, are commonly supposed to be formed by a deposition of stony matter from an aqueous fluid. On the contrary, it is evident from various considerations, respecting their structure and phaenomena, that they are concretions of a peculiar kind, generated by an igneous fluid. They are peculiar to volcanic countries, and differ in every respect from the chrystals produced by the slow and successive precipitation of the stony particles contained in water, Their formation is owing to an intrinsic principle of organization, operating on an ignifled fluid on the concretion of which that principle may be supposed to have operated simultaneously in a large mass, and to have produced these bodies in the same manner, as a linger of metal concretes at once in the mould. ,

In Persia there is a subtertraneous fire of a very harmless nature. It rises out of the ground, about twenty miles from Baku, and three from the Caspian Sea. The ground is rocky, but has a shallow covering of earth. If this be any where scraped off, and fire applied to the places it catches fire immediately, and burns without diminution, nor ever goes out, unless you throw cold earth over it, by which it is easily extinguished. A piece of ground, about two English miles in extent has this wonderful property. In many parts of it there is a continual flame: the chief is in a hole about four feet deep and fourteen in diameter. This is said to have burned many thousand years. stones into lime, by filling a hole in the ground with them, and then putting a lighted candle in the hole. The fire immediately kindles, and in about three days burns the stones sufficiently

It is remarkable, that this flame, how great soever it be, gives .neither smoke nor smell. There is much naphtha all about the place, though not just where the fire is.

Doubtless an inflammable vapour issues in abundance out of the gound in this place. Something of the same kind is found between Bologna and Florence, on the side of one of the Appennines. On a spot of ground three or four miles diameter, there is a constant eruption of fire. The flame rises very high; yet without noise, smoke or smell. In great rains it sometimes intermits, but afterwards burns with the greater vigour. There are three other such fires on the same mountains. - Probably they rise from the veins of bitumen.

A late ingenious writer ascribes all earthquakes to. the same cause, electricity. The impression, says he, they make’ on land and water, to the greatest distance, is instantaneous. This can only be affected by electricity. In the late earthquake, the concussion was : felt through the space of a hundred miles in length, and forty in breadth at the same instant. Now what could throw, a tract of land of four thousand square miles in surface, into such an agitation in a moment No natural power is equal to this, but that of electricity, which alone acknowledges no bounds, neither any sensible transition of time.

The little damage done by most earthquakes, is another argument. for their occasioned by, a simple vibration of the earth through an electric shock. This vibration on the water, meeting with the solid s bottoms of ships, occasions that thump which is felt by them. That

this shakes millions of ordinary houses, and yet not one of them falls, is a farther proof, that it is not a convulsion in the bowels of the earth, but an uniform vibration, like what we occasion in a glass, by rubbing our finger on the edge,, which may be brought to such a pitch, as to break the glass in pieces, by an electric repulsion of its parts.

There can be little doubt, but some earthquakes are owing to electricity but many more are owing to other causes: those of Callao, Port-Royal, for instance, Were unquestionably owing to water: those in the neighbourhood of Aetna and Vesuvius, with those in the East Indies, to lakes of fire. The grand fault is therefore, the ascribing them either to electricity, or any one cause, exclusive of the rest: whereas some are owing to each of these causes: some to several of them acting conjointly.

21. We have inflammable vapours in England, in three or four different places.

One who accurately observed it, gives the following particular account of a burning well. .

“In the latter end of February, ! went to see a spring in the road; which leads from Wigan to Warrington. When we came to it., and applied a lighted candle to the surface of the water, there was suddenly a large and vigorous flame produced. But having filled a cup with water at the flaming place, and held a lighted candle to it, it went out. Yet the water at that place boiled like water over a fire: though when I put my hand into it, it did not feel so much as warm. This boiling seems to proceed from some sulphurous fumes, the spring being not above forty yards from a coal-pit, and all the country for many miles round being underlaid with coal.

When the water was drained away, [applied the candle to the surface of the earth where the water burned before. The fumes took lire and burnt very bright and vigorous, the flame ascending a foot and a half from the ground: and the basis of it was as broad as a man’s bat at the brim. It was not discoloured like that of sulphur, nor had any scent. I ordered a bucket of water to be poured on the lire, and it was immediately quenched.”

22. There was a spring of the same kind at Brosely, near Wenlock, in the county of Salop. It was discovered in June, 1711, by a terrible noise in the night, which awaked several people in their beds, who desiring to know what it was, rose up, and coming to a boggy place under a little hill about two hundred yards from the Severn., perceived a mighty rumbling and shaking of the earth, and a little water boiling up through the grass. When they dug up some of the earth, the water flew up to a great height, and a candle that was in their hand, set the vapour on fire. There is now (viz, in 171]) an iron cistern round the spring, with a cover, having a hole in the middle of it. If you put a lighted candle to the hole, the water takes fire, and burns like spirits of wine. It burns as long as you keep the air from it; but if you take up the cover it goes out. ‘The heat of this fire exceeds that of common lire. Some people, after they have set the water on fire, have put a kettle of water over the cistern, with a joint of meat in it. It was boiled much sooner than it could be, by any artificial fire. If you put wood or even green boughs upon it, it presently consumes them ‘to ashes. The water of itself feels as cold as any common water. Nay, if you put your hand into it as soon as the fire is out it, feels as cold as if there had been no fire near it. But it still continues boiling up, with ‘a considerable noise.

But this well was lost for many years. The poor man in whose land it was, missing the profit lie used to have of showing it, used all his endeavours to find it again; and in May, 1744, hearing a rumbling noise under ground, a little nearer the river than the former well was, he lighted upon it again. For live or six feet deep, it was above six feet wide. Within this was a smaller hole dug in the clay, in the bottom of which was a cylindric earthen vessel, four or five inches diameter, having the bottom taken off, and the sides fixed in the clay. Within the pot was brown water, thick as puddle, continually forced up with a violent motion and a hollow noise, rising arid falling by turns, five or six inches. Upon putting a candle at the end of a stick, within a quarter of a yard, it took fire, darting and flashing in a violent manner, about a half a yard high, much like spirits in a lamp, but with a greater agitation. The man said it had’ made a tea-kettle boil in nine minutes, and that it would burn forty-eight hours without any sensible dimunition. It was extinguished by putting a wet mop upon it. And still the water felt very cold. . ‘

The well lay about thirty yards from the Severn, which in that place, and for some miles above and below, runs in a vale full a hundred yards ‘perpendicular below the level of the country on either side. But the well is now lost again, the water being drawn off by a coalpit.

23.There is a lire’ of the same kind at Pietra Mala, a village on the Appennines. ‘The flame is extremely bright, covers a surface of three yards by two, and usually rises about four feet. After great rains or’ snows, the whole bare patch, about nine yards diameter, flames. The gravel out of which it rises, at a very little depth, is quite cold. There are four of these fires in the neighbourhood: the middle of. the ground whence one of’ them rises, is a little hollowed, and has in it a puddle of water, through which are strong ebullitions of air. This air will not take fire; but that which rises through the wet and cold gravel, flames briskly.

‘In Dauphiny, and some other parts of France, the surface of several springs take the in the same manner on the approach of a candle. Suiphurous vapours undoubtedly exhale from the waters: as is the case in the famous Grotto del Cani.

This lies on the side of a little hill, between Naples and Pozzoli. The sides of it are cut perpendicular in the earth. It is about three feet wide; near twelve feet long; five or six feet high at the entrance, and less than three at the farther end.

The. ground slopes a little from this end to the mouth, and more from thence to the road. If you stand a few steps without, and stoop so as ‘to have, your eye nearly on a level with the ground of the grotto, you may see a vapour within, like that which appears over a chafing dish of red hot coals: only that it ‘is more sluggish, and does not rise above five or six inches high. Its surface more distinctly terminated than that of other vapours, balances visibly under the air as if unwilling to mix with it.

The ground of the grotto is always moist; and so are the sides to the height of ten inches. Yet this never increases so as to form any drops.

While you stand upright, you remark nothing more, than a slight earthy smell, common in all subterraneous places which are kept shut. But if you put down your hand, within ten inches of the ground, it feels as if you put it into the steam of boiling water. Yet your hand contracts neither smell nor taste. A vapour similar to that in the grotto, rises also from the ground without, But it is weaker, and does not rise so high. This partly spreads itself from, the cavern, partly exhales from the earth.

A lighted flambeau thrust in the vapour, presently goes out: yet without any noise or hissing. The thick smoke which appears immediately after its extinction, remains floating on the vapour, and being lighter than it, but heavier than the air above, it spreads between both. Indeed common smoke is lighter than air: but that impregnated with the vapour is heavier.

If a young vigorous dog be held down within the vapour, he at first struggles, pants, snorts, and rattles in the throat. But in three minutes he lies as dead. Carry him into the open air, and he draws in long draughts, as one recovering from a fit, and in two minutes gets upon his legs, and seems to all nothing. A cock having his head plunged into the vapour, was suffocated all at once beyond recovery. Frogs are stupified by it in three or four minutes; yet though they have laid in it a quarter of an hour, soon recover when placed in the open air. Large flies, beetles and butterflies, were longer without giving signs of their suffering, and longer in recovering. A toad resisted the vapour near half an hour, a lizard above an hour and a quarter. And a large grasshopper stirred in the vapour, after being more than two hours in it.

An English gentleman kneeled down in the grotto, and leaning on his hands, bowed his face to within two or the inches of the ground, holding his breath, keeping his eyes open, and his tongue a little out of his mouth. He remained thus, three or four seconds without any’ painful impression, or any sort of taste on his tongue. And hence it manifestly appeared, that this is not a poisonous vapour.

He afterwards advanced his face to the surface of the vapour, and took in breath gently. He was sensible of something suffocating, just like the air of a hot and moist stove. Likewise he felt a slight acrimony in the throat and nose, which made him cough and sneeze: but no head-ach, no sickness at the stomach, nor any other inconvenience.

It is clear, then, upon the whole, that animals die in this vapour, not as poisoned, but rather as drowned, in a fluid not capable of supplying the place of the air, which is necessary for respiration, and equally necessary to sustain fire, as the flame of a lighted flambeau,

24. A fire of a strange nature appeared in Wales, about Christmas, 1693. A fiery vapour came from the sea, and moved up and down for many weeks. It set on fire sixteen ricks of hay, at Harlech in Merzonethslzire and two barns, and annoyed the country, as well by poisoning the grass, as firing the bay. It was a blue, weak flame, and did no harm to the men who tried to save the hay, though they ventured even to touch it. An intelligent person who lived near Harlech, informed his friend some time after, “the fire still continues there. It covers over a part of the sea, from a marshy place in Carnarvonshire, eight or nine miles off. The grass over which it moves kills all manner of cattle that feed upon it; sheep, goats. swine, cows and horses. But what is very remarkable. is, that any great noise, as beating a drum or sounding a horn, effectually repels it from any house, or barn, or stack of hay.”

25.A much stronger flame than that which issues out of the earth, is that which issues out of the stomach of animals. The anatomical lecturer at Pisa, in the year 1 j97 happening to hold a lighted candle near the subject he was dissecting on a sudden set on fire the vapours that came out of the stomach he h id just opened. In the same year, as Dr. Ruisch, then anatomy professor at Pisa, was dissecting a woman, a student lighting him. with a candle, he had no sooner opined the stomach, than there issued out a yellow greenish flame. A like thing happened some years after at Lyons, in dissecting a woman. Her stomach was no sooner opened, than a considerable flame burst out and filled the place. But this is not so much to be wondered at, since the experiments made by Dr. Vulpari, anatomical professor at Bologna. lie affirms any one may gee, issuing from the stomach of an animal, a matter that burns like spirits of wine, if the upper and lower orifices are bound fast with a very strong thread T he stomach thus tied must be cut, above and under the ligature and afterwards pressed with both hands, so as to make all that it contains, pass to one side. This will produce a swelling in that part, which must be held with the left-hand to binder its escaping. A candle then being held about a half an inch from the stomach, let it be suddenly opened by the right-bend, and a bluish flame will immediately gush out, which will sometimes last a minute. In the same way flame may be brought forth from the intestines.

Nor is it from carcasses only that flames have issued. This has been the case with live persons likewise. Bartholine relates, that a popish cavalier, having drank a quantity of brandy, died in a little space, after an eruption of a flame through his mouth. He relates also the case of three others, who after drinking much brandy experienced the same symptom. Two presently died ; the third escaped by immediately drinking cold water. Still more astonishing is’ the case of a woman at Paris, who used to drink brandy to excess. She was one night reduced to ashes by a fire from within, all but her head and the ends of her fingers. In like manner Cornelia Bandi, an aged lady of unblemished life, near Cesena in Romagna, in 1731, re-tired in the evening into her chamber; and in the morning was found in the middle of the room, reduced to ashes, all except her face, skull, three fingers and her legs, which remained entire, with her shoes and stockings. The ashes were light: the floor was smeared with a gross stinking moisture, and the wall and furniture covered with a moist soot, which bad stained all the linen in the chest.

Perhaps a larger account of so remarkable an incident will not be unacceptable to the curious reader.

The countess of Cornelia Bendi, in the sixty-second year of her age, was as well all day, as usual. When she was in bed, she passed two or three hours in talking with her maid: then she fell asleep. The maid going into her chamber in he morning, saw two feet distant from the bed, a heap of ashes, and two legs with the stockings on. Between them was part of the head; but the brains, half the skull, and the whole chin were burnt to ashes. The ashes when taken up, left in the head a greasy and stinking moisture. The bed received no damage: the clothes were raised on one side, as by a person rising from it.

Doubtless the fire was kindled within her by the juices and fermentations in the stomach acting on the many combustible matters, which abound in living bodies, for the uses of life. These in sleep by a full respiration, are put into a stronger motion, and consequently are more apt to take fire, Borelli observes that such accidents often happened, to great drinkers of wine and brandy. Such flames would frequently rise in us, if the natural moisture did not prevent.

Undoubtedly she was burnt standing; hence her skull was fallen between her legs, and the back part of her head was damaged more than the fore part, partly because of her partly because in the face, there were many places, out of which the flames might pass.

An instance of the same kind occurred at Christ Church in Hampshire, on June 26, 1613. One John Hitcheli, a carpenter of that parish, haying ended his day’s work, came borne and went to rest with his wife. 11cr mother being frightened in her sleep called to them for help. None answering, she started up and waked her daughter, who found her husband dead by her side. She dragged him out of her bed into the street; but the heat then forced her to let him go. He lay burning there for three days. Not that there was any appearance of fire outwardly, only a smoke ascending from his carcass, till it was burnt to ashes: except only a small part of his bones which were cast into a pit.

Grace Pett was a fisherman’s wife, of the parish of St. Clement’s, in Ipswich, about sixty. She had a custom for several years of going down stairs every night, after she was undressed, to smoke a pipe. Her daughter who lay with her, did not miss her till the morning, April 10, 1744, when going down stairs, she found her mother’s body extended over the hearth, with her legs on the deal floor, and appeared like a aglowing fire without flame. The neighbours coming in at her cries, found the trunk of her body in a manner burnt to ashes. It then appeared like a heap of charcoal, covered with white ashes, the head, arms, legs, and thighs, were also much burnt. A child’s clothes, on one side of her, and a paper screen on the other were untouched. The deal floor also on which her legs lay, was neither singed nor discoloured.

26.Almost as strange, though not attended with any ill consequence, was the following incident. In November, Mrs. Susanna Sewall, wife to major Sewall, in New England, observed a strange flashing of sparks in all ‘the apparel she put off, which continued till Candlemas. In the company of many persons, she sent for several parts of her wearing apparel, and when they were shaken, sparks flew out, making a noise, much like bay leaves thrown into the tire. One spark lit on major Sewall’s thumb nail, without any heat, and continued at least a minute, before it went out. They caused Mrs. Sewall one day to put on her sister Digge’s petticoat; and when she put it off at night, it sparkled as her own used to do.

27.There is no body but may be by fire converted into glass; not excepting gold itself. And this is the last effect of fire; no art can carry the change of a natural body any farther.

As to the nature and properties of it. 1. Common glass is an artificial compound of salt with sand stones. 2. It is fusible by a strong fire, and when fused, is tenacious and coherent. 3. It does not waste in the fire. 4. When melted it cleaves to iron. 5. When red hot it is-fashionable into any shape, and capable of being blown into a hollowness. which no mineral is. 6. It is frangible when thin, friable when cold, and transparent whether hot or cold. 7. It is flexible, elastic, and dissoluble by cold. It can be cut only by emery or a diamend. 8. It is not dissoluble by aqua fortis, aqua regia, or mercury. 9. Neither acids nor any thing else extract colour, taste, nor any sensible quality from it. 10. It loses nothing either of its substance or of its weight, by the longest and most frequent use. 11. It is not capable of being calcined, neither of contracting rust.

But there is no property of glass more remarkable than its ductility. Glass-spinners draw threads of their brittle matter, melting over a lamp, with far more ease and expedition than common spinners do those of flax or silk. These may be drawn fine as a hair, yea, as the thread of a spider’s web, so as to wave with every wind. And the finer they are, the more flexible. If the ends of two such threads be knotted together, they may be drawn and bent, till the space in the middle of the knot does not exceed the forty-eight part of an inch in diameter.* Near the bay of Acra in Palestine, runs a little river now called Kardanah, supposed to be the ancient Belus, famous for its sand, much used in making glass, and said to have given rise to the invention of it. The Sidonians are reported to have made this discovery, from the following accident. Some travellers having reared a hearth on the sand of this river with large pieces of nitre, and set some fern on fire under a kettle in order to boil their victuals, perceived the sand and the nitre to melt and incorporate with the fern ashes, and presently after, run in a transparent stream, which hardened as it cooled. From hence the hint of making glass was taken, which was gradually improved to its present use and beauty.

* Glass possesses many very astonishing properties: it is accounted one of the most elastic bodies in nature: the rebounding force of glass balls being as 15 to16. When glass is suddenly cooled, it becomes exceedingly brittle, and this may account in some degree, for the singular properties of the Bologna bottle, and glass drop. A most remarkable phenomena is produced in glass tubes, placed in certain circumstances: when these are laid before a fire in a horizontal position having their position properly supported, they acquire a rotatory motion round their axis, and also a progressive motion towards the fire, even when their supports are declining from the fire; so that the tubes will move a little way upwards to (he fire. When the progressive motion of the tubes towards the fire is stopped by any obstacle their rotatory motion still continues. When the tubes are placed in a nearly upright posture. leaning to the right-hand, the motion will be from E. to W. but if they Jean to the left-hand, it will be from W. to E. and the nearer they are placed to the upright posture, the less will be the motion either way. If the tube is placed horizontally on a glass plane, the fragment, for instance, of coach window glass, instead of moving towards the fire, it will move from it, and about its axis, in a contrary direction to what it had done before; nay, it will recede from the fire, and move a little upward, when the plane inclines towards the fire. These experiments are recorded in the Philos. Trans. p. 476. the experimentors succeeded best with tubes about 20 or 22 inches long, which had in each end, a pretty strong pin fixed in cork, for an axis. Glass is less dilatable by heat, than metalline substances, and solid glass sticks, are less dilatable than tubes. The latter have been found to dilate four times as much as the former, in a heat approaching to that of. boiling oil. On account of this property in glass, M. de Luc recommends it to be used in pendulums, its expansions being always equable, and proportioned to the degrees of heat, which is not the case with any other substance yet known. Glass is better adapted for the condensation of vapours, than metallic substances. An open glass filled with water in summer, will gather drops of water on the outside just as far as the water in the inside reaches; and a person’s breath blown on it manifestly moistens it. Glass also becomes moist with dew, in a situation where metals remain dry. A drinking glass partly filled with water, and rubbed on the brim with a wet finger, yields musical notes, of a higher or lower tone, as the glass is more or less full; and makes the liquor leap. Glass is also possessed of great electrical virtues.

28.There are few phenomena relative to glass more hard to be accounted for, than that of the Bologna bottle, so called, because it was’ first discovered at Bologna. If you let these bottles fall from some’ height on a brick floor, they will not be broken; but drop into them some hard body, and they will burst in pieces. I took one of these, says Dr. 1. which held near a pint, and let it fall five feet and a half on a brick floor, and it was not broken. I dropped into it a bit of flint, weighing eleven grains, and immediately it burst in pieces.

I dropped into another bottle a ball of lead, weighing one hundred and forty grains, into a third a piece of brass weighing three hundred grains, and neither of them was broken.

These ‘glasses only differ from common phials in this, they have not cooled gradually in what is called the nealing furnace, but are exposed to the open air as soon as formed. They resist hard blows from without. I have given to some, violent strokes with the mallet, and they have not broke. They likewise do not break, though several-heavy bodies be dropped into them. I have dropped into them from the height of three feet, musket balls, pieces of iron, brass. and gold, without any effect; but when I dropped into it from the height of three inches, a shiver of flint no bigger than a small pea, in about two seconds, the glass flew. Having tried the experiment on several others with the same piece of flint, most of them broke in the moment of the stroke, the rest one or two seconds after it.

I let fall into several glasses a flint of half the size, and they flew in’ like manner. I let fall into one a flint no larger than a grain of sand,- shook the’ glass, and set it down. I did the same with four others. in about half an hour one of them flew, and the other four soon after

I let fall into one a sapphire set in a ring: and though the bottom of the glass was near-an inch thick, the sapphire passed through it as through a spider’s web. r he glass flew all ways, and the ring remained on the table just where it fell.

A bit of China half a line thick, and two lines broad, broke several glasses; so did a bit of glass of the same size: so did diamonds also. And a very small piece of tempered steel broke all the glasses into Which I dropped it.

Some large hollow cups made at Worcester of common green glass, much larger than the others, and some of them above three inches thick at the bottom, though they were not affected by a musket ball, dropped from the height of near three feet, were instantly broken with a shiver of a flint weighing but two grains.

There is something astonishing in the power of telescopes, to bring far distant objects near; and of microscopes, to render those clear and distinct which are quite invisible to the naked eye. And no less amazing in another kind, is the force of burning glasses. 1. A piece of wood, laid before a large burning glass, took tire in an instant. 2. Water contained in an earthen vessel boiled immediately. and in a short time quite evaporated. 3. A mass of lead, three inches thick, began to melt in a moment, and soon after ran in a continued thread. 4. A steel plate grew red hot almost in an instant, and small holes were made through it. 5. Slate becomes black glass ; tiles, yellow’ glass; earthen pots, a darkish yellow glass. 6. A pumice stone, became white glass; earth, black glass ; bones, an opaque one.*

But in the extremely hot weather at Paris, in 1705, the rays of the sun collected by a large glass had scarce any force, though the separate rays quite inflamed the air. The reason of so surprising a thing seems to be, that the heat raised from the earth’s great sulphurous exhalations, embarrassed, stopped, and in some degree absorbed the rays of the sun.

29 Equally strange are the phenomena of the glass drop. The make of this drop is as simple, as its explanation is difficult. They take up a small quantity of melted glass on the top of an iron rod, and let it drop into a pail of water. When it does not break in the operation, it forms the glass drop. This is of such firmness, that it bears smart blows of a hammer without breaking. But if you break only the tip of the small end, the whole shatters into powder. This shattering is attended with a loud report, and the powder scatters all around. If the experiment be made in the air pump, the drop bursts more impetuously, and the dust is finer than when it bursts in the open air. This is a plain matter of fact. I do not undertake to account for it.

Gunpowder is commonly supposed to have been invented by Barthold Schwartz, about the year 1380. But Roger Bacon knew of it, a hundred and fifty years before Schwartz was born. For in his Treatise de Nullitate Magica, published at Oxford in 1216, are these words: “ You may raise thunder and lightning at pleasure, by only

*We have accounts of several burning mirrors, among which, the most remarkable, were those of Settela, canon of Fadua, Villette, a French artist of Lyons, Sir isaac Newton, and Vir. Macquer. That of Settela was 3 Leipsic elli in diameter, and its focus 2 ells distant. Villette's mirror was 4 feet in diameter, ground to a sphere of 76 inches radius; so that its focus was 58 inches from the vertex. Its substance was a composition of tin, copper, and tin glass. Sir Isaac Newton’s mirror, which he presented to the Royal Society, consisted of 7 concave glasses, which were so fixed, that all their foci centered in a phisical point, each of the glasses was a foot in diameter, and six were fixed round the seventh, to which they were all contiguous, and form a segment of a sphere, whose subtense is about inches, and the central glass lies about an inch further in than the rest, the common focus is 22 1/2 inches distant, and about an inch in diameter. This was a mirror of prodigious power.

taking sulphur, nitre, and charcoal, which single have no effect, but mixed together, and confined in a close place, cause a noise and explosion greater than that of a clap of thunder.”

The effect of gunpowder is owing to the spring of the air, enclo and in the spaces between them. All these springs are dilated by the fire, and set a playing at once. The powder itself to light the fire, which puts the air in action.

Aurum falminans. a preparation of gold, is far stronger than gunpowder. A scruple of this acts more forcibly than half a pound of that. A single grain laid on a knife, and lighted at a candle, goes off greater noise than a musket.

30. Air is that clear, transparent, compressible fluid, which is extended at least round the terraqueous globe, being with us about 48,656,000,000 times more dense and sluggish than ether, betwixt and the air there is a very great affinity or attractive force, their density; i. e. the air contiguous to the ether takes in and concentrates the ether proportion ally to its greater density, by which it is rendered more springy and active: with this differerent, that the air by contact and cohesion in the parts of bodies, solid and unelastic, but ether never; from whence again, by heat, fire, ‘or dissolution of parts being separated, its elasticity returns. This element has a near- affinity or relation to water, because it eagerly takes up rarefied water into itself, as water again drinks up a portion of air within its contact; so that air and water, actuated by ether, make the levers and wedges by which nature performs all her changes in bodies. And it serves as the common medium of communication between us and ill bodies

The pressure of a column of sir upon a square inch only is equal to fifteen pounds weight. That upon the surface of a human body, generally amounts t at least thirteen tons weight: seeing all fluids press with an equal force every way, upwards, downwards, sideways, and-in all directions.

“But how is it then that our bodies are not crushed in pieces “ Our bodies, as well as all others, are filled with air throughout: and the spring of the internal air is equal to the pressure of that without. And two equal forces act in contrary directions, they entirely destroy each others effects: hence, if the ambient air press on us, it is all one as if it did not press at all.

The elasticity of the air is a counterbalance to its gravitation. And how necessary is it, that these should balance each other Were the power of gravity to be suspended for a moment, and that of elasticity to remain, the atmosphere would instantly be dissipated through the infinite regions of space. But while the weight of the air and its elastic force are equal, they produce an equillibrium among the particles of air, in every part of the atmosphere.

As the higher it is, the air is more and more expanded, gravitation being less and less, so the parts of the air in the upper regions will be expanded only not to infinity. -

The air is generally invisible. And it is necessary it should be so. For as it is the medium through which we see objects, if the parts of it were perceptible, it would render the view of these objects far less perfect and distinct. Hence a greatly magnifying telescope, as it shows the body of air, makes the view of other objects more confused.

Yet in some cases you may seem to see the air. In a very hot summer’s day, in an open part of the country, place yourself on an eminence, nearly facing the sun. Then, if there be a gentle wind, there will be a reflection of light from the body of the air in the vale below. And you will see the undulations or waves of air almost as perfectly as you may those of water, agitated by a gentle wind, And yet in truth, it is not the air which you see, but the vapours that float therein.

One property of air is its weight or gravity. This you will immediately feel, if you lay your hand on the mouth of a vessel, which is emptied of air. If you lay a square piece of glass on the orifice of an air-pump, when the air is drawn out, it will be broke to shivers with a great noise. Or extract the air from between two smoothly polished marbles, and close the edges with wax, they will then be so strongly pressed together, as not easily to be separated. But we need no other proof of it than the barometer: a glass tube, close at one end, and filled with mercury. Immerge the other end in a basin of the same fluid, and when it is erected, the mercury in the tube will rise thirty inches above the surface of that in the basin.

The changes then in the barometer are wholly owing to the changes in the weight of the atmosphere. But to what are these owing It seems chiefly to the winds. For, 1. These must alter the weight of the air in any particular place, either by bringing together and accumulating the air, which is the case when two winds blow at the same time from opposite points; or by sweeping away part of the air, as when two winds blow opposite ways from the same point; or lastly, by cutting off the pressure of the atmosphere, which happens when any wind blows briskly any way. 2. Cold nitrous particles load the atmosphere, and increase its weight. 3. So do heavy, dry exhalations from the earth. 4. The air being rendered heavier is more able to support the vapours, which being intermixed with it, make the weather fair and serene. When it is rendered lighter by the contrary causes, it becomes unable to support the vapours, which then sink, gather into drops, and fall into rain.

With us the mercury is highest when the wind is north or northeast, and so brings the cold condensed air of the northern climates. In all northern countries the mercury varies more than in the southern, the winds being more frequent, strong, various, and opposite to each other. - Between the tropics it scarce varies at all, the winds being small, and generally blowing the same way.

The pressure of the air, is, caeter is paribus, as its height. Carry the’ barometer to a higher place, where the incumbent column of air shorter, and a shorter column of air is sustained: it being found to ‘descend at the rate of a quarter of an inch for every hundred feet of ascent.

Now air, as all other fluids, must press equally every way. Hence it is, that soft bodies sustain their pressure, without any change of figure, and brittle bodies without breaking, though that pressure be equal to that of a column of mercury thirty inches high, or a column of water of thirty feet. Nothing can keep these bodies unchanged, but the equal pressure on all sides, which resists as much as it is resisted. And hence on removing or lessening that pressure on one side, the effect of it is soon perceived on the other. -

It is by means of its gravity 1. That the air closely invests the earth with all the bodies on it, and bends them down; that it prevents the arterial vessels of plants and animals from being too much distended, by the impetus of the circulating juices, and that it hinders the blood from oozing out, through the pores of their containing vessels. Hence, they who travel up high mountains, the higher they ascend, are relaxed the more. till they fall into spitting of blood. 2.. The mixture of contiguous fluids is chiefly owing to this. Hence many fluids which readily mix in the air, when that is removed remain separate. 3 It determines the action of one body upon another. Thus it presses the particles of hre against the fuel ‘Whereas upon removing the air the fire immediately goes out So aqua regia ceases to dissolve gold, if the air be taken away: hence, also on the tops of high mountains, as on the Peak of Teneriffe, the most acrid bodies, such as pepper, ginger, salt, have no sensible taste, for want of a sufficient gravity in the air to press their particles into the pores of the tongue.

Another property of air is elasticity. It yields to an impression, by contracting its dimensions, and returns to them, on removing the impressive cause. This endeavour to expand itself, every particle of air continually exerts, against an equal endeavour of the ambient particles. Hence it is, that a bladder full of’ air. will burst in an exhausted -receiver: while one that before seemed empty, swells and appears to be full of air.

This power does not seem to have any bounds. Nor is it easy to be destroyed. Let air be expanded ever so much, it still retains its spring. Nor is this sensibly diminished by any experiment which has yet been made.

There is no fixing bounds to its condension, any more than to its dilation. It will dilate, into a thousand times its former space, yea into 13,679 times. And all this by its own expansive force, without any force of lire. The air we breathe near the surface of the earth is compressed by its own weight, into at least the 13,679th part of the space it would possess in vacuo. And if the same air be farther condensed by art, the space it will take up when most dilated, will be (according to Mr. Boyle) to that it possessed when most condensed, as 550,000 to one.

If while we increase the elasticity of air, on one side by compression, we increase it on the other side by heat, the force of’ both soon becomes irresistible ; and a French philosopher supposed, that air thus confined and expanding was sufficient for the explosion of a world. In order to determine the elasticity of air, the wind-gun has been invented, which is an instrument that compresses a large quantity of air into a tube in which there is an ivory ball, and then gives the compressed elastic air free power to act and drive the ball as directed. The ball thus driven will pierce a thick board, and will be as fatal at small distances, as if driven with gunpowder. I do not know whether ever the force of this instrument has been assisted by beat; certain I am, that this, which could be very easily contrived by means of phosphorous, or any other hot substance applied to the barrel, would give such a force as I doubt whether gunpowder itself could produce.

Every thing we see gives of its parts to the air, and has a little floating atmosphere of its own round it. The rose is encompassed with a sphere of its own odorous particle; while the nightshade infects the air with scents of a more ungrateful nature. The perfume of musk flies off in such abundance, that the quantity remaining becomes sensibly lighter. A thousand substances that escape all our senses, we know to be there; the powerful emanations of the load-stone, the effluvia of electricity, the rays of light, and the insinuation of fire. Such are the various substances through which we move, and which we are constantly taking in at every pore, and returning again with an imperceptible discharge.

This great mixture of all earthly bodies is continually operating upon itself; which, perhaps, may be the cause of its unceasing motion; bat it operates still more visibly upon such grosser substances, as are exposed to its influence; for scarce any substance is found capable of resisting the corroding qualities of the air. The air say the chemists, is a chaos furnished with all kinds of salts and menstruums; and therefore it is capable of dissolving all kinds of bodies.

It is well known that copper and iron are quickly eaten with rust; and that in the climates near the equator, no art can keep them clean. In those countries, instruments, knives, and keys, though kept in the pocket, nevertheless are quickly incrusted; and the great guns, with every precautions after some years, become useless. Stones may be supposed to be more easily soluble. The marble of which the noble monuments of Italian antiquity are composed, although in one of the finest climates in the world, nevertheless show the impressions which have been made .upon them by the air. in many places they seem worm eaten by time; and in others they appear crumbling into dust. Gold alone seems to be exempted from this general dissolution. It is never found to contract rust, though exposed never so long: the reason is, that sea salt, which is the only menstruum of gold, is but very little mixed with the air, being a very fixed body, and not apt to volatilize. In the laboratories, however, where the air is impregnated with it, gold is found to rust, as well as other metals.

By its. elasticity, air insinuates into the pores of bodies, carrying with it this faculty of expansion; whence it must necessarily put all the particles it is mixed with, into perpetual oscillations. And as its elasticity is never the same for two moments together, there must be an incessant dilation and contraction in all bodies. To this is owing all putrefaction and fermentation, neither of which will proceed in vacuo. And indeed all natural corruption and alteration seem to depend hereon: so that metals, particularly gold, are so durable, only by being impervious to air. And yet it may be doubted, whether air itself be the true, original, universal dissolvent; or rather the etherial fire, which is intimately united with every particle of it: and without which air is effete and useless, neither able to feed flame, nor to Sustain animal life.

That there is some matter in the air much finer than the air itself, appears from many considerations. In an exhausted receiver something remains, which conveys the heat near as readily as air. Now this must be a body, and a body subtle enough to penetrate the pores of glass. Doubtless then it penetrates the pores of all other bodies, and consequently is diffused through the universe. And this seems to be not only more subtle than the air, but far more weighty and elastic. To the weight of this may be owing the weight of the air, and of all other bodies : to its elasticity, the elasticity of the air, and of all other elastic bodies. This also may cause the reflection and other phaenomena of light: as also sensation, and muscular motion. Indeed it seems to be the first spring of all the action in the universe.

Air is sometimes deprived of its elasticity, and wrought into the substance of other bodies, from which nevertheless it may be extracted, and resume its elastic state. As to animal substances, a very considerable quantity of air is extracted from them by distillation, not only from the blood and fat, but also from the most solid parts of animals. Half a cubic inch of a fallow deer’s horn, produced 117 cubic inches of air ; half a cubic inch of oyster shells, no less than 162 cubic inches.

As to vegetable substances, half a cubic inch of heart of oak generated 108 cubic inches; a cubic inch of peas 396 cubic inches, or 113 grains, which was above a third of its weight, This air will flash, if touched with a candle.

Camphire generates no air: brandy next to none: well water or rain water a little, Pyrmont water, twice as much: which air contributes to the briskness of this and other mineral waters.

From minerals much air may be extracted. Half an inch of Newcastle coal yielded 180 inches of air, which weighed near one third of the coal.

Yet good part of the air extracted from these bodies, in some days gradually lose its elasticity : because the acid, and sulphurous fumes, raised with the air, resorbed and fixed the elastic particles- But when a means was found, to prevent this, it lost only a seventeenth or eighteenth part; and that chiefly in the first twenty-four hours; the first was permanently elastic.

There is another way of producing air. which seems to be more natural; namely, by fermentation. A cubic inch of * oil of vitriol with half an inch of sal ammoniac, generated six cubic inches of air: six inches of powdered oyster shells, and an equal quantity of white wine vinegar, generated twenty-nine inches.

That much air is incorporated into the substance of vegetables, appears from the following experiments.

Forty-two inches of ale from the tan, generated in three months 636 cubic inches of air: twelve inches of Malaga raisins, in six weeks, generated 411 inches: twenty-six inches of apples, in thirteen days, generated 968 inches of air. They then in—three or four days resorbed about twelve inches, and afterwards neither generated nor resorbed

That the air arising from distilled or fermenting bodies, is true air, appears from hence: that it continues in the same expanded state for weeks, or months, which expanded vapours will not do. And that it is elastic, appears by its dilating and contracting with heat and cold, as common air does.

Air then makes a very considerable part of the substance of vegetables as well as animals. And besides these particles of air, which strongly adhere to, and are wrought into their substance, there is in. them a large quantity which is upon the wing, and in a very active state.

Mr Geoffry shows, that the mixture of any vitriolic salts with inflammable substances, will yield common brimstone: particularly of oil of vitriol with oil of turpentine. Brimstone, therefore, is nothing but vitriolic salt united with some combustible substance.

‘To show’ how much air is contained in white paper, take as many slips of as weigh a hundred grains ; burn these warily by the flame of a candle, and then weigh the ashes. You will find the hundred grains reduced to six. So ninety-four grains out of one hundred, are undeniably transformed into air. They could not be annihilated; anti they could not rise and fly away without a repelling force to carry them

Thus the candle itself;, is by degrees transformed from heavy palpable wax, into a light, impalpable body of air. But observe: all bodies which thus become air, pass through the intermediate state of flame. So that properly speaking. the same body was one moment paper, the second moment fire, and the third air. How different states for the same sort of matter to subsist in, in so short a time!

The air-pump shows how much air is, even in water. Place a tall glass of water in the receiver; turn the winch, and you see bubbles of air through the body of the water First they arc thick, but small; then they grow large and rise to the top of the water and as long as the pump works, so long the air rises but more slowly, and in lar bubbles In wine the air bubbles rush violently to the top and burst Nay and the liquor perfectly boils, like water on the fire Yea, and hot water may be made to boil by the air pump, as well as by fire. ‘Hence, it appears, that boiling is nothing but the motion produced from the expansion of the air, whether by fire, or by the warmth and pump conjointly.

By another experiment, it appears, that any piece of wood is pervious to the air, and that its air vessels run through the whole length or substance of the tree. Nay, quicksilver may be made to pass through piece of wood and descend in the form of a shower of rain

By the air pump we likewise measure the weight and that a pint of it weighs 8 grains. Consequently, a gallon weighs a little more than a drachm; therefore a bushel weighs an ounce and a half a drachm.

Another experiment proves what one would not suspect. Bodies moving in a fluid, meet so much the more resistance, as their bulk is larger in equal weight. So a cork of equal weight with a guinea, meets with so much the more resistance from the air. But in an exhausted receiver, the largest bulk of cork, which was before the most resisted, now proves the heavier body, and accordingly falls more swiftly than the gold.

Again Strike a flint against the steel in vacuo, and it will occasion no sparks. So necessary is air to the very appearances of fire.

Air ‘is generated likewise from minerals by fermentation. By other fermenting mixtures it is absorbed again, and by others generated and absorbed alternately.

A quarter of an inch of filings of iron, and an inch of compound aqua-fortis, in four days absorbed 27 inches of air, When hot water was poured upon it, it generated three or four inches, which after some days it absorbed again. A quarter of an inch of iron filings, with an inch of powdered brimstone, absorbed nineteen inches in two days. Powdered brimstone mixed with Newcastle coal, neither generated nor absorbed.

An inch of chalk, and as much oil of vitriol, in three days generated 31 inches of air. Part of this it afterwards resorbed. Two inches of lime and as much sal ammoniac absorbed 1 15 inches. The fumes of this are therefore very suffocating. . All burning and flaming bodies, absorb much air. And whereas the air which some substances absorb, is afterwards remitted; that which is absorbed by burning brimstone, by the flame of a candle, or by human respiration, does not recover its elasticity.

The elasticity of the air in the vesicles of the lungs is continually decreasing, through the vapour it is there loaded with, so that there needs fresh air continually; otherwise those vesicles will soon fall flat, whereby the motion of the blood through the lungs being stopped instant death ensues. And this seems to be exactly the case of most of those who are killed by lightning, which so totally destroys the elastic air in the lungs, that they instantly fall flat.

31. Many have imagined that the animal fluids are furnished with air by the lungs only. But undoubtedly they are also supplied therewith, by way of the chyliferous canals: and that in no small quantity. For the air, like all other animal fluids, requires to be perpetually renewed ; accordingly old particles fly off every moment, and new ones succeeded in their place.

It may be demonstrated, that urine contains much air. Doubtless so does the perspirable matter: which being the lightest of all animal fluids, is the chief vehicle of the effete and useless air.

And that candles soon go out, if they are confined in a small quantity of air, seems not to be so much owing to their having rendered the air effete by consuming its vivifying spirit, as to its destroying the elasticity thereof, by its acid, fuliginous vapours.

But nothing destroys the elasticity of air like brimstone, whether burning or in fermenting mixtures. And as the attractive power of bodies, is found to be more or less, as they have more or fewer sulphurous particles, so we may reasonably ascribe the fixing the elastic particles of air, to the strong attraction of the sulphurous particles, with which Sir Isaac Newton suppose all bodies to abound. more or less.

The various mixtures in the stomach, sometimes generate, sometimes absorb air. In a good digestion, the generating power exceeds the absorbing power but a little. When it exceeds it much we are troubled more or less, with disteuding flatuses.

We have seen how much air may be extracted from animal and vegetable bodies, Into whose substances it was before intimately and firmly incorporated And consequently great quantities of air must be continually expended in their production. Fart of this we see, may resume its elastic state, when their texture is dissolved; but part probably never regains its elasticity, at least not in many centuries. However, we may see what immense treasures of this important element the wise Author of nature has abundantly provided: the constant waste of it being abundantly supplied, by heat or fermentation flow innumerable dense bodies.

If all the parts of nature were endued with a strongly attracting power only, whole nature would immediately become one unactive cohering lump. It was therefore absolutely necessary there should be every where intermixed, a due proportion of strongly elastic particles. And since abundance of these are continually reduced from an elastic to a fixed state, it was also necessary that these particles should be endued with a property of resuming their elasticity, whenever they were disengaged from that mass, in which they were fixed. And hereby this beautiful frame of things, is maintained in a continual round, of the production, and dissolution of animal and vegetable bodies.

The air is very instrumental in the production and growth of animals and vegetables: in its elastic state, by invigorating their juices: and in its fixed state, by greatly contributing to the union and firm connexion of their constituent parts. It is also a very powerful agent in the dissolution of the same bodies.

32. That fixed air* is a cementing principle, appears (to omit. others) from that well known experiment. Quicklime dissolves flesh, by extracting and imbibing the fixed air, which it contained. But while the flesh hills in pieces from the loss of the principle, the lime grows solid by having it restored.

That it contributes also to the dissolution of bodies appears hence. During the progress of putrefaction, a volatile matter flies continually from the putrefying substance. And this is no other than air, which is now extricated and thrown off from a fixed and unelastic state, but immediately returns to it again, on meeting with a proper recipient.

*Air was long considered as a simple elementary substance, but now it no longer ranks as an element in the chemical vocabulary. Within the last half century, the discoveries respecting air have been so numerous and rapid as to raise the doctrine of it, to the dignity of a science. A numerous list of different airs has been supplied by the practical philosophers, all of which exhibited very different specific properties. We read in the treatises on this subject, of inflammable air, sulphurated inflammable alkaline air; nitrous air, hepatric air, atmospherical air; and vitriolic, nitrous, marine and other acid airs, &e. But these abstract airs are termed in the new nomenclature gasses. As oxygen, nitrogen, hydrogen. carbonic acid, &c. The latter of which is what is understood by fixed air.

The preserving bodies from putrefaction, depends almost in every instance, on restraining the flight of the fixed air. For as this cements their constituent parts, so putrefaction which is the disunion of them, cannot take place while this remains.

And this air both corrects and prevents putrid acrimony in the animal fluid. Hence any food which does not contain a due proportion of it, is found to promote putrefaction: as do all damaged vegetables, which being incapable of fermentation, are incapable of producing the due quantity of air.

But pure air is no where to be found. That which surrounds us is the most heterogeneous body in nature. It is no other than an universal chaos, a colluvies of all kinds of bodies. No bodies can withstand the force of fire. And whatever fire can volatilize is found in the air. Hence, for instance, the whole fossil kingdom must be found therein: for all that tribe is convertible into fume. Gold, the most fixed of all, adheres to sulphur in mines, and is raised along with it. All the parts of the animal kingdom must likewise be in the air. For besides the copious effluvia they emit by perspiration, (whereby an animal in the course of its duration, impregnates the air with many times the quantity of its own body) any dead animal when exposed to the air, is in a certain time carried wholly off. And we know that all vegetables by putrefaction become volatile, and so evaporate into air.

Air, 2. Volatilizes fixed bodies. Thus sea salt being calcined and fused, then exposed to the air to liquefy; when liquefied, set to dry again; then fused again, and the operation thus repeated will dry by degrees, be almost wholly evaporated, nothing remaining but a little earth.

Air, 3. Fixes volatile bodies. Thus though aqua-fortis or spirit of nitre, readily evaporates by the fire; yet if the air near be impregnated with spirit of urine, the volatile spirit is fixed, and falls down in a liquid form.

But the air, being open or enclosed, is of consequence in chemical operations. So, to make sulphur inflammable, a free air is required: in a close vessel it will not kindle. And thus all animals and vegetables can only be calcined in open air. In close vessels they never become any other than black coals.

By the air-pump the air is in a great measure drawn out of a vessel called a receiver. And hence we learn how much all vital. nutritive and alternative powers depends upon the air. A candle in the exhausted receiver usually goes out in a minute. A kindled charcoal is totally extinguished in about five minutes. Red hot iron is not affected thereby; only it will not light sulphur or gunpowder, but melt it. Loadstones act as well as in the open air. Smoke sinks in a darkish body to the bottom, leaving the upper part clear and transparent.The syphon does not run therein: but attrition produces heat, as in the open air. If some grains of a heap of gunpowder be kindled by a burning-glass they will not fire the contiguous grains. Glow-worms lose their light as the air is exhausted but recover it not on its re-admission. Vipers and frogs seem dead in less than two hours; but recover in the open air. Snails live ten hours; efts two or three days; leeches five or six.

The atmosphere is a body of air and vapours, which surrounds the globe to the height of at least sixty miles, gravitates towards its centre, and is carried along with it in all its motions. This continually presses on our bodies, with a weight equal to a pillar of air, whose base is equal to the surface of our bodies. Now a pillar of air of the height of the atmosphere, is equal to a pillar of water thirty-two feet high. Every foot square therefore of the surface of our bodies is pressed on by a weight of air, equal to 35 cubic feet of water: and a cubic foot of water weighing 76 pounds, troy weight; consequently every foot square of the surface of our bodies sustain a pillar of air, equal to 2,260 pounds. If then the surface of a man’s body contains fifteen square feet he sustains a weight equal to 39,900 pounds. This is the case when the air is heaviest. But the difference between the greatest and the least, pressure of air upon our bodies is equal to 3,982 pounds.

Hence it is so far from being a wonder, we should sometimes suffer in our health by a change of weather, that it is the greatest wonder we should not always suffer. For when we consider our bodies are at some times pressed upon by near two tons weight more than at others, it is-surprising that every change does not break our whole frame to pieces.

In, truth the vessels of our bodies being so much straitened by an increased pressure, would stagnate the blood to the very heart, had not the Author of nature wisely contrived, that when the resistance of its circulation is greatest, the force by which the heat contracts should be so too. For upon an increase of the weight of the air, the lungs are more strongly expanded, and the blood, by being more intimately broken, made fitter for finer secretions, the nervous in particular, by which the heart is more strongly contracted. On the other hand, when the weight of the ambient air is ever so little abated, the air contained within the blood, unfolds its springs, and forces the blood to take up a larger space than it did before.

The reason we are not sensible of this pressure, is well explained by Borrelli: sand perfectly rammed into a hard vessel, cannot be penetrated even by a wedge. And water in a bladder, compressed on all sides, cannot give way in any part. In like manner, within the skin of an animal, are contained various parts; some hard as bones: some soft as muscles: and some fluid as blood. Now it is not possible that bones should be broke or displaced in the body, unless the pressure lay heavier on one part than another. If the pressure be so divided, that it be equal all round, upward, downward, sideways, and no part of the skin to be exempt therefrom, it is plain, no fracture or luxation can follow.

The same may be observed of the muscles and nerves, which though soft, yet being composed of solid fibres, do mutually sustain each other, and resist the common weight. The same holds of the blood and other humours. As water is not capable of condensation, so these liquids, while contained in these vessels, cannot be forced out of them by an universal compression. Add to this, that the air itself, which is contained in every part of the body, is such a balance to the external air, that no hurt can ensue from its pressure.

33.Oil of vitriol, when exposed to the air, continually increases in weight. Let a phial of this stand unstopped, and it will be constantly running over. Perhaps the cause of this odd phenomenon is, the moisture contained in the air, which this Liquor, a potential fire, imbibes as greedily, as actual fire does nitre.

34.At the height of forty-one miles, the air is so rarefied, as to take up three thousand times the space it does here. At fifty-three miles high, it would be expanded thirty thousand times as much as it. is here.

At that distance, as was observed, it is expanded into three thou. sand times the space it occupies here. And we have seen it condensed into the sixteenth part of the same space. It seems then, that the air is capable of being condensed into the hundred and eighty thousandth part of the space it would take up when free from pressure. But what texture must it be of, to make it capable of this immense expansion and contraction! How imperfectly is this accounted fort by comparing it to wool, cotton, and the like elastic bodies.

35.But there is an amazing difference between the fixed and the common air, with regard to their effects upon animal bodies. The fixed air, even when set free, and in a state of perfect elasticity, whether it be during the first stage of fermentation by fire, by effervescence, or by putrefaction; if it be received into the lungs of any animal, causes instant death. But the same air when received into the stomach, whether thrown off by effervescent mixtures in medicines, or extricated from the food by natural fermentation; in the first instance often operates like a charm, in restraining vomitings; and in the second is absolutely needful for the support of life and health.

With regard to the common air, on the contrary, no animal can live tong without taking large quantities of it into the lungs. Yet if a small portion of it be forced into the blood-vessels of any animal, death presently ensues. So that these two species of air, have quite different provinces, with respect to animal life. The first, common air, must mix wholly with the blood. The second only communicates some subtle matter to it: probably electric fire, which we know is connected with every particle of common air.