I received your favours. The book and prints which Mr. Argand was so obliging as to deliver I have since sent to Sir Joseph Banks agreable to your request. I am very much obliged to you for your observations on the alteration of the wood of the box belonging to the magnets. Since I received your favour have been endeavouring to make as simple an instrument as possible, a drawing of which I have here sent. If you should at your leisure consider it and if you find that its not adequate to the purpose wanted should esteem it as a great favour if you’d inform me of it or if any Alterations or additions can be added to it. I was the day before yesterday at Windsor where Mr. De Luc shewed me an Hygrometer it was made of a thin piece of whale bone about nine inces long was kept strait by a line fasten’d to it going over a pulley the other end of which line was fastned to a spiral spring. He observed that it was the only substance he had ever met with that would always return to the same length when soaked in water. It altered in its length about one inch from extreame Moisture to extream dryness. A Day or two ago Mrs. Clark called on me. She desired her duty to you when I wrote and desired I would inform you she had lost her only Brother in the Ville de Paris.

Mrs. Nairne Polly and Fanny desire to be particularly remembred to you. Hope you enjoy a good state of health as they at present do, they were not a little flattered that you mentioned them in your letter. I sent you sometime ago the account of shortning wire by Lightning which I hope you have received. Mr. Magellan undertook to have it sent to you. I am Dear Sir Your most obliged Humble Servant