To William Jones
Paris. Dec. 10. 1788.
The bearer hereof, Mr. Parker, being to return to Paris in a few days, furnishes me a safe conveiance for a couple of thermometers for which I have occasion, and which I beg the favor of you to send me by him: the one about 8. inches long graduated from boiling water down to about 20°. of Farenheit below nought;1 the other not less than 18. inches long, and graduated from boiling water down to the congelation of spirits of wine. Both of them to have Farenheit’s graduation on the right of the one side of the tube and Reaumur’s on the other. They are intended to be hung on the outside of a glass window, with the face of the plate next to the window so that it may be seen without opening the window. The best method of rendering the thread of mercury visible in this situation is, I beleive, to make a slit in the plate, under the tube. Be so good as to have this done, and if experience has established any convenient kind of frame for thermometers placed against the window in the manner I propose, I would wish to receive them with such frames. The larger thermometer being intended occasionally for nice experiment, be pleased to pay great attention to it’s exact graduation. Mr. Parker will be so good as to let you know the day of his departure from London, and to pay you for them on delivery. I will beg of you not to let me lose so good a chance of having them safe brought. I am Sir your very humble servt.,
PrC (DLC). TJ erred by putting this letter in SJL Index under “Jones Wm. (Bristol)”; it should have been entered under “Jones Wm. Mathem. Instr.” (London).
1. This word interlined in substitution for “freezing,” deleted.