The curious discovery was related by Benjamin Franklin (1706-1790) to Jan Ingenhousz (1730-1799) in this week’s letter, which is from Houghton’s Autograph File. Ingenhousz was physician to the court of Austria at the time, and a fellow of the Royal Society who later settled in England. Franklin was in London for his extended second trip to Britain, and had just over a month before been taken to task by the privy council over what they deemed treasonable activities.
Though Franklin begins the letter with thanks for Ingenhousz’s support, the most interesting part of this letter for me is the conclusion, when he moves from current events to the discoveries of science and the learned community. The “curious discovery” of the title does not involve Mr. Franklin on a hillside during a thunderstorm, with kite and key in hand, but concerns instead another scholar.
Mr. Walsh, (one of whose Papers on the Torpedo I shall, to save Postage, send you thro’ the Hands of the Ambassador) has just made a curious Discovery in Electricity. You know we find that in rarify’d Air it would pass more freely, and leap thro’ greater Spaces than in dense Air; and thence it was concluded that in a perfect Vacuum it would pass any distance without the least Obstruction. But having made a perfect Vacuum by means of boil’d Mercury in a long Torricellian bent Tube, its Ends immers’d in Cups full of Mercury, he finds that the Vacuum will not conduct at all, but resists the Passage of the Electric Fluid absolutely, as much as if it was Glass itself. This may lead to new Principles and new Views in the atmospheric Part of Philosophy.
John Walsh (1726-1795) was a fellow of the Royal Society who studied the electrical transmission of the Torpedo fish. Franklin took it upon himself to widely disseminate Walsh’s paper, and in this letter even added a drawing to help Ingenhousz understand the experiment that Walsh had performed.
A transcription of the letter is available through the digital edition of the Papers of Benjamin Franklin.
This post is part of a weekly feature on the Houghton Library blog, “You’ve Got Mail,” based on letters in Houghton Library. Every Friday this year a Houghton staff member will select a letter from the diverse collections in the Library and put that letter into context. All posts associated with this series may be viewed by clicking on the You’veGotMail tag.
[This post was contributed by James Capobianco, Reference Librarian.]
