me, that you were to be from home for some time after the writing of it; and I had my mind engaged in a chain of thinking that I was unwilling to interrupt, as that season was the only time of the year in which I could hope to pursue it without interruption. My design was to show, by the best observations made in the space of two hundred and seventy years, that the theory of the motion of the planets, which I have formed, agrees better with the appearances in the heavens than any theory hitherto published; and that tables may be formed on that theory more correct than any that have hitherto appeared, without excepting those formed by Dr. Halley and published so lately as 1749, which I can show, from Mr. Flamsteed's and Lord Maclesfield's observations, to be almost everywhere faulty. This I am the more fond of, because it is not so much for the pleasure of imagination and amusement, as of real use, but attended with exceeding great care, attention, and trouble.

You have given me an anxious longing to see your answer to the Abbé Nollet's objections to your theory, as I make no doubt of its being made more evident thereby, and cleared from any obscurities, which such things are unavoidably subject to, at first appearing, especially with those that are not much conversant with the subject. Persons who write in the manner the Abbé does, not for the sake of truth and information, but to secure or gain a reputation, seldom avoid losing what they chiefly intend to preserve. The justice, which I hear is done to your merit by the Royal Society, makes full recompense for these little abuses, and I heartily congratulate you upon it. It you think proper to communicate your answer to the Aboé Nollet to me, before you transmit it, you may assure yourself of my making remarks with that free

dom which should always subsist between friends, and with less care of exposing my own want of knowledge, than of observing on every thing that I shall think may want correction.

I am, &c.

CADWALLADER COLDEN.

FROM CADWALLADER COLDEN TO P. COLLINSON.

DEAR SIR,

On Water-Spouts.

Coldenham, 28 May, 1754.

Your favor of the 10th of March surprised me, by finding that you had a copy of a letter, which I wrote last fall, or beginning of winter, to Mr. Franklin on water-spouts; because I did not write it with any thoughts, that it would have gone farther than for his private perusal; but, since you take notice of it as a novelty, which destroys the commonly received opinion, you lay me under some necessity of adding something more to it. For, as to the facts therein related, they are certainly true as far as I can trust my eyes and ears. I did, at the time, commit the account of what I saw to writing; but it is so long since, that these, with several other observations made about that time, are lost, or perhaps some one of my friends got the perusal of them, and has not restored them. But the appearance made so strong an impression on me, that I dare trust to my memory, even at this distance of time; and perhaps few, who were curious enough to observe this phenomenon, without being prejudiced by received opinions, if any have had an opportunity of

viewing a water-spout so near them, as I did this, without receiving some injury from it; and indeed the master and sailors were more anxious from the danger of its approach, in preparing against the danger, than in observing it accurately as I did.

I saw several others in the same voyage, at a greater distance, and, from all of them, I am as fully convinced as I can be of any thing from my senses, that the common opinion of sucking up the sea-water is false. If the water had been sucked up, there must have been a rising in the sea directly under the point of the spout; whereas there 'was a hollow in the sea, which I distinctly saw, and the spray rising round the hollow as happens by the force of wind from the pipe of a pair of bellows. The avoiding of the danger by firing a shot through the pipe, which you mention as an objection, confirms rather than weakens what I say, by giving a horizontal vent to the wind, by which it goes over the ship, and does not strike.

If you consider the particulars in the description of the spouts, which I saw, as I wrote them to Mr. Franklin in that and in a subsequent letter, you will be convinced that the spout was not formed by sucking water. I would not have it thought that, in my opinion, never any great quantity of rain or water falls from those clouds. On the contrary, I think, that, after the fermentation in the clouds, which supports them in the air and generates the wind, is lessened or ceases, then they may fall in prodigious pouring showers, but not confined to the diameter of two or three yards, as the wind from the spout is. The rain, I believe, never or seldom falls at the time the spout is seen, but afterwards and at distances from that place. If the clouds sucked up the sea-water, when it fell again it must at least be brackish. I cannot conceive how the

sucking up of sea-water can divest it of its saline qualities; or if the water were divested of its salt in the clouds, the salt must fall down again somewhere to the sea or land. Salt water, I think, was never observed to come from the clouds.

Mr. Franklin tells me, that another gentleman was of the same opinion with me, of wind issuing from the water-spout, though neither of us knew the other's opinion, and I am still ignorant of the facts on which he formed his.

As you have my former papers on whirlwinds, &c., I now send you an account of one which I had lately an opportunity of seeing and examining myself.

Being in Maryland, riding with Colonel Tasker, and some other gentlemen, to his country-seat, where I and my son were entertained by that amiable and worthy man with great hospitality and kindness, we saw, in the vale below us, a small whirlwind beginning in the road, and showing itself by the dust it raised and contained. It appeared in the form of a sugarloaf, spinning on its point, moving up the hill towards us, and enlarging as it came forward. When it passed by us, its smaller part near the ground appeared no bigger than a common barrel; but, widening upwards,

it seemed, at forty or fifty feet high, to be twenty cr thirty feet in diameter. The rest of the company stood looking after it; but, my curiosity being stronger, I followed it, riding close by its side, and observed its licking up, in its progress all the dust that was under its smaller part. As it is a common opinion that a shot, fired through a water-spout, will break it, I tried to break this little whirlwind, by striking my whip frequently through it, but without any effect. Soon after, it quitted the road and took into the woods, growing every moment larger and stronger, raising, instead of dust, the old dry leaves with which the ground was thick covered, and making a great noise with them and the branches of the trees, bending some tall trees round in a circle swiftly and very surprisingly, though the progressive motion of the whirl was not so swift but that a man on foot might have kept pace with it; but the circular motion was amazingly rapid. By the leaves it was now filled with, I could plainly perceive, that the current of air they were driven by, moved upwards in a spiral line; and when I saw the passing whirl continue entire, after leaving the trunks and bodies of large trees which it had enveloped, I no longer wondered that my whip had no effect on it in its smaller state. I accompanied it about three quarters of a mile, till some limbs of dead trees, broken off by the whirl, flying about and falling near me, made me more apprehensive of danger; and then I stopped, looking at the top of it as it went on, which was visible, by means of the leaves contained in it, for a very great height above the trees. Many of the leaves, as they got loose from the upper and widest part, were scattered in the wind; but so great was their height in the air, that they appeared no bigger than flies. My son, who was by this time come up with me, followed the whirlwind till it left the woods,