Philada, Feb. 4., 1753.
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I AGREE with you, that by means of a vacuum in a whirlwind, water cannot be suppos'd to rise in large masses to the region of the clouds: for the pressure of the surrounding atmosphere could not force it up in a continu'd body or column, to a much greater height than thirty feet. But if there really is a vacuum in the center, or near the axis of whirlwinds, then I think water may rise in such vacuum to that height, or to less height, as the vacuum may be less perfect.
I had not read Stuart's Acct. in the Transactions, for many years before the receipt of your letter, and had quite forgot it; but now, on viewing his drafts, and considering his descriptions, I think they seem to favour my hypothesis: For he describes and draws columns of water, of various heights, terminating abruptly at the top, exactly as water would do when forc'd up by the pressure of the atmosphere into an exhausted tube.
I must, however, no longer call it my hypothesis, since I find Stuart had the same thought, tho' somewhat obscurely express'd, where he says, "he imagines this phenomenon may be solv'd by suction (improperly so called), or rather pulsion, as
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Publication information: Book title: The Ingenious Dr. Franklin:Selected Scientific Letters of Benjamin Franklin. Contributors: Nathan G. Goodman - Editor, Benjamin Franklin - Author. Publisher: University of Pennsylvania Press. Place of publication: Philadelphia. Publication year: 1931. Page number: 198.
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