ed 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.

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 common air in weight, than the watery coat exceeds a like bulk of common air in gravity.

This was the objection in my mind, though, I must confess, I know not how to account for the watery coat's encompassing the air, as above mentioned, without allowing the attraction between air and water, which the 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.

The gentleman observes, "that a certain quantity of moisture should be every moment discharged and taken away from the lungs ;" and hence accounts for the suffocating nature of snuffs of candles, as impregnating the air with grease, between which and water there is a natural repellency; and of air that hath been frequently breathed in, which is overloaded with water, and, for that reason, can take no more air. Perhaps the same observation will account for the suffocating nature of damps in wells.

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 vapors, so full as that they continually precipitated. Do not we see the air overloaded, and casting forth water plentifully when there is no suffocation?

The gentleman again observes, "that the air under the equator, and between the tropics, being constantly heated and rarefied by the sun, rises; its place is supplied by the air from northern and southern latitudes, which, coming from parts where the air and earth had less motion, and not suddenly acquiring the quicker motion of the equatorial earth, appears an east wind blowing westward; the earth moving from west to east, and slipping under the air."

In reading this, two objections occurred to my mind. First, that it is said, the trade-wind 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 trade-wind must appear either as a southeast or northeast wind; south of the equator, a southeast wind; north of the equator, a northeast. For the apparent wind must be compounded of this motion from north to south, or vice versâ; and of the difference between its motion from west to east, and that of the equatorial air.

Observations in Answer to the Foregoing; by Benjamin Franklin.

READ AT THE ROYAL SOCIETY, NOVEMBER 4TH, 1756.

1. THE supposing a mutual attraction between the particles of water and air is not introducing a new law of nature; such attractions taking place in many other known instances.

2. Water is specifically eight hundred and fifty 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 eight hundred and fifty times the space it did before it formed the bubble; and within the bubble should be either a vacuum, or air rarefied more than eight hundred and fifty times. If a vacuum, would not the bubble be immediately crushed by the weight of the atmosphere? And no heat, we know of, will rarefy air any thing near so much; much less the common heat of the sun, or that of friction, by the dashing on the surface of the water. Besides, water agitated ever so violently produces no heat, as has been found by accurate experiments.

3. 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.

4. Was ever a visible bubble seen to rise in air? I have made many, when a boy, with soap-suds and 2 tobacco-pipe; but they all descended when loose from the pipe, though slowly, the air impeding their motion. They may, indeed, be forced up by a wind from below, but do not rise of themselves, though filled with warm breath.

5. The objection relating to our breathing 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 let 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 of moisture during a shower, than at other times when it does not rain at all. The dewy dampness, that settles on the insides of our walls and wainscots, seems more certainly to denote an air overloaded with moisture; and yet this is no sure sign; for, after a long-continued cold season, if the air grows suddenly warm, the walls, &c. continuing longer their coldness, will, for some time, condense the moisture of such air, till they grow 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.

6. It is, I think, a mistake, that the trade-winds blow only in the afternoon. They blow all day and all night, and all the year round, except in some particular places. The southerly sea-breezes on your coasts, indeed, 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 sixty days, which could not be if the wind blew only in the afternoon.

7. That really is, which the gentleman justly supposes ought to be on my hypothesis. In sailing southward, when you first enter the trade wind, you find it northeast, or thereabouts, and it gradually grows more east as you approach the line. The same ob.. servation is made of its changing from southeast to east gradually, as you come from the southern latitudes to the equator.

Observations on the Meteorological Paper; sent by Mr. Cadwallader Colden to B. Franklin.

READ AT THE ROYAL SOCIETY, NOVEMBER 4TH, 1756.

19 November, 1753.

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.

It seems to me, for the same reason, equally absurd to give a mutual attractive power between any other