I did my self the pleasure of writing to you the 8th of last Month and sent it to your grandson. I last night had the pleasure of seeing him at the Royal Society. He told me he was detained longer than he expected. But that he should go Sunday or Monday next which oppertunity I have taken of sending you the identical hygrometer, I mentioned in mine of the 8th of Octr. that I took down to Ramsgate. It has never grown so dry as to be equal to that which I kept in London, though before I took it down they moved very well together. I hear there is a wonderful Electrical Machine at Paris made of oiled silk, Major Gardener tole me that the single sparks drawn from it are sufficient to knock down an Ox, that he sparks are two or three inches thick and about three feet long. When I have the pleasure of hearing from you, if you would favor me with some Account of its construction it would be an addition to the many favors already received by Dear Sir Your Most Obliged Humble Servant