Whilst I am writing to a Philosopher and a Friend, I can scarcely forget that I am also writing to the greatest Statesman of the present, or perhaps of any century. Who spread the happy contagion of Liberty among his countrymen; and like the greatest Man of all antiquity, the Leader of the Jews, deliver’d them from the house of bondage, and the scourge of oppression.

I can with difficulty descend to plain prose, after these sublime ideas, to thank you for your kindness to my son Robt. Darwin in France, and to converse with you about what may arise in philosophy, which I know will make the most agreable part of my letter to you.

1. Mr. Bennet, a Curate in my neighbourhood, has found out a method of doubling the smallest conceivable quantity of either plus, or minus electricity, till it becomes perceptible to a common electrometer, or increases to a spark. It is thus. He has three brass plates about 4 or 6 inches diameter. C is a brass plate varnished on its upper surface, lying on an electrometer like Cavello’s except that it has two slips of gold leaf hanging down instead of threads and balls. Mr. Bennet, to try the electricity, the atmosphere, takes a coated Phial in one hand into the open air; and holding up a blazing candle above his head, touches the lower part of the flame with the knob, holding the coating in his other hand. 2. then He comes into the house, and with the knob touches the plate C. (which is insulated by being laid on the glass electrometer of Cavallo.) and then lays the plate b on C and touches it with his finger. (nb. the handle of this plate, and of a are insulating handles.) then the electricity recieved by the coated phial is divided between that phial, and the two plates C and b, which have a varnish between them. 3. Then He separates the plate b from C. & puts on b the plate a. (which is varnish'd on the underside) & touches that plate a. Then he separates a from b. Now as b was contrary to c. a is the same as C. He then touches C with the edge of the plate a, and at the same times applies the plate b over C. and repeats the process 5-10-or 50 times, and thus the electricity is continually doubled. Or very nearly so. Because one inch of the surface of a coated electric will absorb or recieve perhaps 100 times as much as will continue on such a surface of a conductor in contact with it.

This is likly to be of service in detaching the small quantities of electricity given out in chemical processes, or atmospheric changes. De Luc’s idea of two electric fluids, like water and heat is I think very ingenious, and perhaps true.

In respect to other philosophical news, I have just heard from Mr. Wedgewood that Mr. Herschel has discover’d three Volcanoes in the Moon now burning.

Since I had the pleasure of seeing you, I have removed from Lichfield to Derby, and have superintended a publication of a translation of the botanical works of Linnaus, viz, The System of Vegetables in two volumes 8vo. also. I did this with design to propagate the knowlege of Botany. They are sold to the booksellers at 14/ the System of Vegetables. The The Genera will be finished in a month, and will be sold to the booksellers at 12s. I believe. But as we are to pay for advertizing and carriage, I expect we shall not clear more than 10s. on each set. If the work had been finished I should have sent you it by the favor of Mr. Nicklin, who is so kind as to take the care of this letter. If I thought 20 sets of each were likely to be sold I would send them at 10s. a set of each, that is 20s. for the four volumes. And indeed would now have sent them by Mr. Nicklin, had the whole been ready. As I think they would not be worth reprinting in America, and perhaps 20 sets would be as many as would find purchasers.

A Line from you at your leizure, only to acquaint me that you continue to possess a tollerable share of health would be very acceptable to, dear Sir with true esteem Your most obedient servant