[ 359 ] 



XXVI. An Account of a new Electrometer^ 

 contrived by Mr, William Henly, and of 

 fever al EleElrical Experiments made by 

 him^ in a Letter from Dr. Prieftley, F.RS. 

 to Dr. Franklin, F..R.S. 



Dear Sir, 



Head May r8,y THINK myfelf happy in an oppor- 

 I7/2 ' JL tunity of giving you a fpecies of plea— 

 'fure, which I know is peculiarly grateful to you as- 

 the father of modern electricity, by tranfmitting to 

 you an account of fome very curious and valuable 

 improvements in your favourite fcience. The author 

 of them is Mr. Henly, in 'the Borough, who has 

 favoured me with the communication of them, and 

 has given me leave to requefl, that you would pre- 

 sent them to the Royal Society. 



In my hiflory of electricity, and elfewhere, I have 

 mentioned a good electrometer, as one of the greateft 

 deiiderata among practical electricians, to meafure 

 both the precife degree of the electrification of any 

 body, and alfo the exact quantity of a charge be- 

 fore the explofion, with refpect to the fize of the 

 electrified body, or the jar or battery with which it, 

 is connected j as well as to afcertain the moment of 

 time, in which the electricity of a jar changes, when, 

 without making an expiolion, it is difcharged by 



g ivin g 



