Front Page Titles (by Subject) CV: TO THOMAS CLAP 1 - The Works of Benjamin Franklin, Vol. II Letters and Misc. Writings 1735-1753
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CV: TO THOMAS CLAP 1 - Benjamin Franklin, The Works of Benjamin Franklin, Vol. II Letters and Misc. Writings 1735-1753 
The Works of Benjamin Franklin, including the Private as well as the Official and Scientific Correspondence, together with the Unmutilated and Correct Version of the Autobiography, compiled and edited by John Bigelow (New York: G.P. Putnam’s Sons, 1904). The Federal Edition in 12 volumes. Vol. II (Letters and Misc. Writings 1735-1753).
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TO THOMAS CLAP1
Philadelphia, 8 November, 1753.
The first intimation I find of the new air-pump is in a piece of Mr. Watson’s read to the Royal Society, February 20th, 1752, where, describing some experiments he made in vacuo, he says: ‘The more complete the vacuum, cæteris paribus, the more considerable were the effects; and here I should not do justice to real merit were I silent in regard to Mr. Smeaton. This gentleman, with a genius truly mechanical, which enables him to give to such philosophical instruments as he executes a degree of perfection scarce to be found elsewhere; this gentleman, I say, has constructed an air-pump by which we are empowered to make Boyle’s vacuum much more perfect than heretofore. By a well conducted experiment, which admits of no doubt as to its truth, I have seen by this pump the air rarefied to one thousand times its natural state; whereas, commonly, we seldom arrive at above one hundred and fifty. As the promotion of the mechanic arts is a considerable object of our excellent institution, if this gentleman could be prevailed upon to communicate to the Royal Society that particular construction of his air-pump which enables it to execute so much more than those commonly in use, it would not fail to be an acceptable present.”
So far Mr. Watson. In April following, was read a letter from Mr. Smeaton, in which he describes his improvement, and gives a draft of his pump; the whole too long to transcribe; but it appears to me that the machine, being rather simplified than made more complex, can scarce cost more than one of the old sort, though the price is not mentioned. By only turning a cock it is at pleasure made a condensing engine; an advantage the others have not.
I have seen nothing of your searchers. Mr. Parker has received Bower, but writes me that he is at a loss how to send it, and desires you would order somebody to call for it.
I shall send the dollars for Mr. Mix per next post; for I fancy you will not now buy this apparatus here, but choose the new air-pump from England.
With my respects to all friends, I am, &c.,