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with air, it would weigh at least as much less, | less motion, and not suddenly acquiring the as this difference between the weight of that quicker motion of the equatorial earth, apincluded air, and that of water. pears an east wind blowing westward; the Now although this would do nothing to ac-earth moving from west to east, and slipping count for the dissolution of salt in water, under the air." the smallest lumps of salt being no more hollow spheres, or any thing of the like nature, than the greatest; yet, perhaps, it might account for water's rising and being supported in air. For you know that such hollow globules, or bubbles, abound upon the surface of the water, which even by the breath of our mouths, we can cause to quit the water, and rise in the air.

These bubbles I used to suppose to be the coats of water, containing within them air rarefied and expanded with fire, and that therefore, the more friction and dashing there is upon the surface of the waters, and the more heat and fire, the more they abound.

In reading this, two objections occurred to my mind :-First, that it is said, the tradewind doth not blow in the forenoon, but only in the afternoon.

Secondly, that either the motion of the northern and southern air towards the equator is so slow, as to acquire almost the same motion as the equatorial air when it arrives there, so that there will be no sensible difference; or else the motion of the northern and southern air towards the equator, is quicker, and must be sensible; and then the tradewind must appear either as a south-east or north-east wind : south of the equator, a southeast wind; north of the equator, a north-east. For the apparent wind must be compounded of this motion from north to south, or vice versa; and of the difference between its motion from west to east, and that of the equatorial air.

And I used to think, that although water be specifically heavier than air, yet such a bubble, filled only with fire and very rarefied air, may be lighter than a quantity of common air, of the same cubical dimensions, and, therefore, ascend; for the rarefied air enclosed, may more fall short of the same bulk of Observations in answer to the foregoing. common air, in weight, than the watery coat exceeds a like bulk of common air in gravity. Read at the Royal Society, Nov. 4, 1756. This was the objection in my mind, though, 1st. THE supposing a mutual attraction beI must confess, I know not how to account tween the particles of water and air, is not for the watery coat's encompassing the air, introducing a new law of nature; such atas above-mentioned, without allowing the at-tractions taking place in many other known traction between air and water, which the instances. gentleman supposes: so that I do not know but that this objection, examined by that sagacious genius, will be an additional confirmation of the hypothesis.

2dly. Water is specifically 850 times heavier than air. To render a bubble of water, then, specifically lighter than air, it seems to me that it must take up more than 850 times The gentleman observes, “that a certain the space it did before it formed the bubble; quantity of moisture should be every moment and within the bubble should be either a vadischarged and taken away from the lungs; cuum or air rarefied more than 850 times. If and hence accounts for the suffocating nature a vacuum, would not the bubble be immediateof snuffs of candles, as impregnating the air ly crushed by the weight of the atmosphere? with grease, between which and water there And no heat, we know of, will rarefy air any is a natural repellency; and of air that hath thing near so much; much less the common been frequently breathed in, which is over-heat of the sun, or that of friction by the dashloaded with water, and, for that reason, caning on the surface of the water: besides, watake no more air. Perhaps the same obser- ter agitated ever so violently produces no heat, vation will account for the suffocating nature of damps in wells.

as has been found by accurate experiments.

3dly. A hollow sphere of lead has a firmness and consistency in it, that a hollow sphere or bubble of fluid unfrozen water cannot be supposed to have. The lead may support the pressure of the water it is immerged in, but the bubble could not support the pressure of the air, if empty within.

But then if the air can support and take off but such a proportion of water, and it is necessary that water be so taken off from the lungs, I queried with myself how it is we can breathe in an air full of vapours, so full as that they continually precipitated. Do not we see the air overloaded, and casting forth wa- 4thly. Was ever a visible bubble seen to ter plentifully, when there is no suffocation? rise in air? I have made many, when a boy, The gentleman again observes," That the with soap-suds and a tobacco-pipe; but they air under the equator, and between the tro- all descended when loose from the pipe, though. pics, being constantly heated and rarefied by slowly, the air impeding their motion: they the sun, rises; its place is supplied by air from may, indeed, be forced up by a wind from benorthern and southern latitudes, which, com-low, but do not rise, of themselves, though ing from parts where the air and earth had filled with warm breath.

Observations on the Meteorological Paper; sent by Cadwallader Colden, of New York, to B. Franklin.-Read at the Royal Society, Nov. 4, 1756.

5thly. The objection relating to our breath- | ing moist air seems weighty, and must be farther considered. The air that has been breathed has, doubtless, acquired an addition of the perspirable matter which nature intends to free the body from, and which would be pernicious if retained and returned into the blood such air then may become unfit for respiration, as well for that reason, as on account of its moisture. Yet I should be glad to learn, by some accurate experiment, whether a draft of air, two or three times inspired, and expired, perhaps in a bladder, has, or has not, acquired more moisture than our common air in the dampest weather. As to the precipitation of water in the air we breathe, perhaps it is not always a mark of that air's being overloaded. In the region of the clouds, indeed, the air must be overloaded if it lets fall its water in drops, which we call rain; but | those drops may fall through a drier air near the earth; and accordingly we find that the hygroscope sometimes shows a less degree It seems to me, for the same reason, equalof moisture, during a shower, than at other ly absurd to give a mutual attractive power times when it does not rain at all. The dewy between any other particles supposed to be at dampness, that settles on the insides of our a distance from each other, without any thing walls and wainscots, seems more certainly to intermediate to continue their mutual action. denote an air overloaded with moisture; and I can neither attract nor repel any thing at a yet this is no sure sign: for, after a long distance, without something between my continued cold season, if the air grows sud-hand and that thing, like a string, or a stick; denly warm, the walls, &c. continuing longer nor can I conceive any mutual action without their coldness, will, for some time, condense some middle thing, when the action is continuthe moisture of such air, till they grow ed to some distance. equally warm, and then they condense no more though the air is not become drier. And, on the other hand, after a warm season, if the air grows cold, though moister than before, the dew is not so apt to gather on the walls. A tankard of cold water will, in a hot and dry summer's day, collect a dew on its outside; a tankard of hot water will collect none in the moistest weather.

THAT power by which the air expands itself, you attribute to a mutual repelling power in the particles which compose the air, by which they are separated from each other with some degree of force; now this force, on this supposition, must not only act when the particles are in mutual contact, but likewise when they are at some distance from each other. How can two bodies, whether they be great or small, act at any distance, whether that distance be small or great, without something intermediate on which they' act? For if any body act on another, at any distance from it, however small that distance be, without some medium, to continue the action, it must act where it is not, which to me seems absurd.

The increase of the surface of any body lessens its weight, both in air, and water, or any other fluid, as appears by the slow descent of leaf-gold in the air.

The observation of the different density of the upper and lower air, from heat and cold, is good, and I do not remember it is taken notice of by others; the consequences also are well drawn; but as to winds, they seem prin6thly. It is, I think, a mistake that the cipally to arise from some other cause. trade-winds blow only in the afternoon. They Winds generally blow from some large tracts blow all day and all night, and all the year of land, and from mountains. Where I live, round, except in some particular places. The on the north side of the mountains, we fresoutherly sea-breezes on your coasts, indeed,quently have a strong southerly wind, when blow chiefly in the afternoon. In the very long run from the west side of America to Guam, among the Philippine Islands, ships seldom have occasion to hand their sails, so equal and steady is the gale, and yet they make it in about 60 days, which could not be if the wind blew only in the afternoon.

they have as strong a northerly wind, or calm, on the other side of these mountains. The continual passing of vessels on Hudson's River, through these mountains, give frequent opportunities of observing this.

In the spring of the year the sea-wind (by a piercing cold) is always more uneasy to me, accustomed to winds which pass over a tract of land, than the north-west wind.

7thly. That really is, which the gentleman justly supposes ought to be, on my hypothesis. In sailing southward, when you first enter the You have received the common notion of trade-wind, you find it north-east, or there water-spouts, which, from my own ocular abouts, and it gradually grows more east as observation, I am persuaded is a false concepyou approach the line. The same observa- tion. In a voyage to the West Indies, I had tion is made of its changing from south-east an opportunity of observing many waterto east gradually, as you come from the south-spouts. One of them passed nearer than ern latitudes to the equator. thirty or forty yards to the vessel I was in.

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which I viewed with a good deal of attention; and though it be now forty years since I saw it, it made so strong an impression on me, that I very distinctly remember it. These waterspouts were in the calm latitudes, that is, between the trade and the variable winds, in the

month of July. That spout which passed so near us was an inverted cone, with the tip or apex towards the sea, and reached within about eight feet of the surface of the sea, its basis in a large black cloud. We were entirely becalmed. It passed slowly by the vessel. I could plainly observe, that a violent stream of wind issued from the spout, which made a hollow of about six feet diameter in the surface of the water, and raised the water in a circular uneven ring round the hollow, in the same manner that a strong blast from a pair of bellows would do when the pipe is placed perpendicular to the surface of the water; and we plainly heard the same hissing noise which such a blast of wind must produce on the water. I am very sure there was nothing like the sucking of water from the sea into the spout, unless the spray, which was raised in a ring to a small height, could be mistaken for a raising of water. I could plainly distinguish a distance of about eight feet between the sea and the tip of the cone, in which nothing interrupted the sight, which must have been, had the water been raised from the sea.

In the same voyage I saw several other spouts at a greater distance, but none of them whose tip of the cone came so near the surface of the water. In some of them the axis of the cone was considerably inclined from the perpendicular, but in none of them was there the least appearance of sucking up of water. Others of them were bent or arched. I believe that a stream of wind issued from all of them, and it is from this stream of wind that vessels are often overset, or founder at sea suddenly. I have heard of vessels being overset when it was perfectly calm, the instant before the stream of wind struck them, and immediately after they were overset; which could not otherwise be but by such a stream of wind from a cloud.

That wind is generated in clouds will not admit of a dispute. Now if such wind be generated within the body of the cloud, and issue in one particular place, while it finds no passage in the other parts of the cloud, I think it may not be difficult to account for all the appearances in water-spouts: and from hence the reason of breaking those spouts, by firing a cannon-ball through them, as thereby a horizontal vent is given to the wind. When the wind is spent, which dilated the cloud, or the fermentation ceases, which generates the air and wind, the clouds may descend in a prodigious fall of water or rain. A remarkable intestine motion, like a violent fermentaVOL. II.... 2 X

tion, is very observable in the cloud from whence the spout issues. No salt-water, I am persuaded, was ever observed to fall from the clouds, which must certainly have happened if sea-water had been raised by a spout.

Answer to the foregoing Observations, by B. Franklin.-Read at the Royal Society, Nov. 4, 1756.

I AGREE with you, that it seems absurd to suppose that a body can act where it is not. I have no idea of bodies at a distance attracting or repelling one another without the assistance of some medium, though I know not what that medium is, or how it operates. When I speak of attraction or repulsion, I make use of those words for want of others more proper, and intend only to express effects which I see, and not causes of which I am ignorant. When I press a blown bladder between my knees, and find I cannot bring its sides together, but my knees feel a springy matter, pushing them back to a greater distance, or repelling them, I conclude that the air it contains is the cause. And when I operate on the air, and find I cannot by pressure force its particles into contact, but they still spring back against the pressure, I conceive there must be some medium between its particles that prevents their closing, though I cannot tell what it is. And if I were acquainted with that medium, and found its particles to approach and recede from each other, according to the pressure they suffered, I should imagine there must be some finer medium between them, by which these operations were performed.

I allow that increase of the surface of a body may occasion it to descend slower in air, water, or any other fluid: but do not conceive, therefore, that it lessens its weight. Where the increased surface is so disposed as that in its falling a greater quantity of the fluid it sinks in must be moved out of its way, a greater time is required for such removal. Four square feet of sheet lead sinking in water broadways, cannot descend near so fast as it would edgeways, yet its weight in the hydrostatic balance would, I imagine, be the same, whether suspended by the middle or by the corner.

I make no doubt but that ridges of high mountains do often interrupt, stop, reverberate, or turn the winds that blow against them, according to the different degrees of strength of the winds, and angles of incidence. I suppose too, that the cold upper parts of mountains may condense the warmer air that comes near them, and so by making it specifically heavier, cause it to descend on one or both sides of the ridge into the warmer valleys, which will seem a wind blowing from the mountains.

Damp winds, though not colder by the ther- times appearing with a small bending, or elmometer, give a more easy sensation of cold bow, in the middle. I never saw any hang than dry ones, because (to speak like an elec- perpendicularly down. It is small at the trician) they conduct better; that is, are bet- lower end, seeming no bigger than one's arm, ter fitted to convey away the heat from our but still fuller towards the cloud from whence bodies. The body cannot feel without itself; it proceeds. our sensation of cold is not in the air without the body, but in those parts of the body which have been deprived of their heat by the air. My desk, and its lock, are, I suppose, of the same temperament when they have been long exposed to the same air; but now if I lay my hand on the wood, it does not seem as cold to me as the lock; because (as I imagine) wood is not so good a conductor, to receive and convey away the heat from my skin, and the adjacent flesh, as metal is. Take a piece of wood, of the size and shape of a dollar, between the thumb and finger of one hand, and a dollar, in like manner, with the other hand: place the edges of both, at the same time, in the flame of a candle: and though the edge of the wooden piece takes flame, and the metal piece does not, yet you will be obliged to drop the latter before the former, it conducting the heat more suddenly to your fingers. Thus we can, without pain, handle glass and china cups filled with hot liquors, as tea, &c. but not silver ones. A silver tea-pot must have a wooden handle. Perhaps it is for the same reason that woollen garments keeping the body warmer than linen ones equally thick; woollen keeping the natural heat in, or, in other words, not conducting it out to air.

In regard to water-spouts, having, in a long letter to a gentleman of the same sentiment with you as to their direction, said all that I have to say in support of my opinion; I need not repeat the arguments therein contained, as I intend to send you a copy of it by some other opportunity, for your perusal. I imagine you will find all the appearances you saw, accounted for by my hypothesis. I thank you for communicating the account of them. At present I would only say, that the opinion of winds being generated in clouds by fermentation, is new to me, and I am unacquainted with the facts on which it is founded. I likewise find it difficult to conceive of winds confined in the body of clouds, which I imagine have little more solidity than the fogs on the earth's surface. The objection from the freshness of rain-water is a strong one, but I think I have answered it in the letter above mentioned, to which I must beg leave, at present, to refer you.

Extracts from Dampier's Voyages.-Read at the Royal Society, December 16, 1756. A SPOUT is a small ragged piece, or part of a cloud, hanging down about a yard seemingly, from the blackest part thereof. Commonly it hangs down sloping from thence, or some

When the surface of the sea begins to work, you shall see the water for about one hundred paces in circumference foam and move gently round, till the whirling motion increases; and then it flies upwards in a pillar, about one hundred paces in compass at the bottom, but gradually lessening upwards, to the smallness of the spout itself, through which the rising sea-water seems to be conveyed into the clouds. This vissibly appears by the clouds increasing in bulk and blackness. Then you shall presently see the cloud drive along, though before it seemed to be without any motion. The spout also keeping the same course with the cloud, and still sucking up the water as it goes along, and they make a wind as they go. Thus it continues for half an hour, more or less, until the sucking is spent, and then breaking off, all the water which was below the spout, or pendulous piece of cloud, falls down again into the sea, making a great noise with its falling and clashing motion in the sea.

It is very dangerous for a ship to be under a spout when it breaks; therefore we always endeavour to shun it, by keeping at a distance, if possibly we can. But for want of wind to carry us away, we are often in great fear and danger, for it is usually calm when spouts are at work, except only just where they are. Therefore men at sea, when they see a spout coming, and know not how to avoid it, do sometimes fire shot out of their great guns into it, to give it air or vent, that so it may break; but I did never hear that it proved to be of any benefit.

And now we are on this subject, I think it not amiss to give you an account of an accident that happened to a ship once on the coast of Guinea, some time in or about the year 1674. One capt. Records of London, bound for the coast of Guinea, in a ship of three hundred tons, and sixteen guns, called the Blessing, when he came into latitude seven or eight degrees north, he saw several spouts, one of which came directly towards the ship, and he having no wind to get out of the way of the spout, made ready to receive it by furling the sails. It came on very swift, and broke a little before it reached the ship, making a great noise, and raising the sea round it, as if a great house, or some such thing, had been cast into the sea. The fury of the wind still lasted, and took the ship on the starboard-bow with such violence, that it snapt off the boltsprit and foremast both at once, and blew the ship all along, ready to overset it; but the ship did presently right

ceived much wind in it as it passed by."—Vol. iii. page 223.

Account of another Spout—from the same. "WE saw a spout but a small distance from

again, and the wind whirling round, took the ship a second time with the like fury as before, but on the contrary side, and was again like to overset her the other way: the mizenmast felt the fury of this second blast, and was snapt short off, as the foremast and boltsprit had been before. The mainmast and main-us; it fell down out of a black cloud that top-mast received no damage, for the fury of the wind (which was presently over) did not reach them. Three men were in the foretop when the foremast broke, and one on the boltsprit, and fell with them into the sea, but all of them were saved. I had this relation from Mr. John Canby, who was then quarter-master and steward of her; one Abraham Wise was chief-mate, and Leonard Jefferies second

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Account of a Spout on the coast of New

Guinea from the same.

"WE had fair clear weather, and a fine moderate gale from south-east to east by north; but at day-break the clouds began to fly, and it lightened very much in the east north-east. At sun rising the sky looked very red in the east near the horizon; and there were many black clouds both to the south and north of it. About a quarter of an hour after the sun was up, there was a squall to the windward of us, when, on a sudden, one of our men on the forecastle, called out that he saw something astern, but could not tell what. I looked out for it, and immediately saw a spout beginning to work within a quarter of a mile of us, exactly in the wind; we presently put right before it. It came very swiftly, whirling the water up in a pillar, about six or seven yards high. As yet I could not see any pendulous cloud from whence it might come; and was in hopes it would soon lose its force. In four or five minutes time it came within a cable's length of us, and passed away to leeward; and then I saw a long pale stream coming down to the whirling water. This stream was about the bigness of a rainbow. The upper end seemed vastly high, not descending from any dark cloud, and, therefore, the more strange to me, I never having seen the like before. It past about a mile to the leeward of us, and then broke. This was but a small spout, and not strong nor* lasting; yet I per* Probably if it had been lasting, a cloud would have

been formed above it. These extracts from Dampier, seem, in different instances, to favour both opinions,

yielded great store of rain, thunder, and lightning. This cloud hovered to the southward drew to the westward a great pace, at which of us for the space of three hours, and then time it was that we saw the spout, which hung fast to the cloud till it broke, and then the cloud whirled about to the south-east, then to the north-east, where meeting with an island, it spent itself, and so dispersed; and immediately we had a little of the tail of it, having had none before.”—Vol. iii. page 182.

C. Colden to Dr. Franklin.-Read at the
Royal Society, December 6, 1756.

April 2, 1754.

ANY knowledge I have of the winds, and other changes which happen in the atmosphere, is so very defective, that it does not deserve the name; neither have I received any satisfaction from the attempts of others on this subject. It deserves then your thoughts, as a subject in which you may distinguish yourself, and be useful.

Your notion of some things conducting heat or cold better than others, pleases me, and I If I rememwish you may pursue the scent. ber right, Dr. Boerhaave, in his chemistry, thinks that heat is propagated by the vibration of a subtle elastic fluid, dispersed through the atmosphere and through all bodies. Sir Isaac Newton says, there are many phenomena to prove the existence of such a fluid: and this opinion has my assent to it. I shall only observe that it is essentially different from that which I call ether; for ether, properly speaking, is neither a fluid nor elastic; its power consists in re-acting any action communicated to it, with the same force it receives the action.

I long to see your explication of waterspouts, but I must tell you before hand, that it will not be easy for you to convince me that the principal phenomena were not occasioned by a stream of wind issuing with great force, my eyes and ears both concurring to give me this sentiment, I could have no more evidence than to feel the effects, which I had no inclination to do.

It surprises me a little, that wind, generated by fermentation is new to you, since it may be every day observed in fermenting liquor. You know with what force fermenting liquors will burst the vessels which contain them, if the generated wind have not vent; and with what force it issues on giving it a

and, therefore, are inserted entire, for the reader's consideration.

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