Calibration of Hen ly electrometer 



281 



The second column shows the quantity of electricity in the jar, which must 

 diminish each time in the ratio of 15 to 16, and the other column is the number 

 which the electrometer stood at in the different experiments. 



The above experiment is supposed to have been made in the autumn of 1772. 



569] Separation of Henly's electrometer when fixed in the usual way and on 

 an upright rod. 



Aug. 13, 1773. Th. about 78. 



Henly's electrometer was stuck on a thin wooden rod 25 inches long, the 

 end of which was fixed into the hole made in the conductor for receiving the 

 electrometer, being parallel to the conductor as usual. The conductor to which 

 this was fixed was connected to the other conductor which received the elec- 

 tricity from, the machine by a brass wire about 10 inches long, and a jar with 

 Lane's electrometer fastened to it was made to communicate with this last 

 conductor, so that the rod to which the electrometer was fastened was about 

 * inches from the globe and * inches from the jar. 



Henly's electrometer was then compared with Lane's while in this situation, 

 and when this was done the wooden rod was taken away and Henly's placed 

 on the conductor in the usual manner, everything else being the same as before, 

 and compared with Lane's as before. 



N.B. In both trials the cork ball of Henly's was turned from the globe f. 



The result was as follows: 



Hence it appears that when 

 Henly's [electrometer] is fixed on 

 the rod it is more sensible towards 

 the beginning of its motion than 

 afterwards, whereas when put in 

 the usual way it is the contrary. 



570] Result of P. 70, 75, & 95 [Arts. 540, 544, 559], being a comparison of 

 the different electrometers. 



[bo in MS.] 



[Of the electrical machine.] 



