The first Intimation I find of the New Airpump, is in a Piece of Mr. Watson’s, read to the Royal Society, Feb. 20. 1752 where describing some Experiments he made in Vacuo, he says, “The more compleat the Vacuum, caeteris 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 impower’d 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 rarified to 1000 Times its natural State; whereas commonly we seldom arrive at above 150. As the promotion of the mechanic Arts is a considerable Object of our excellent Institution, if this Gentleman could be prevail’d 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 the] April following, was read a Letter from Mr. Smeaton in which he describes his Improvements, and [gives a] Draft of his Pump; the whole too long to transcribe but it appears to me that the Machine being rather simplify’d than made more complex, can scarce cost more than one of the old Sort, tho’ the Price is not mention’d. 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 receiv’d 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 chuse the new Airpump from England.

My Respects to all Friends, concludes, from Dear Sir, Your obliged humble Servant