Comparisons of electrometers 265 

 A plate of rosin and bees wax of the same proportions as for exper. rosin 

 A c 



was cast of the shape of figure, ABDC and abed being brass plates 2-45 in. 

 diam. their distance before the rosin was poured in being about -12 inc. 



Tu. Feb. 23 [1773] in afternoon, the rosin plate being cast that morning, 

 the hygrom. as well as I remember being about 22. 

 [4 observations, comparison with E.] 

 Wed. Feb. 24 [1773]. Th. 54. N. 20. [4 observations.] 

 Spreading of electricity on surface. 

 Rosin closed in about 7", sep. again in 35. 

 E was irregular. 



545] Second thermometer tube; also comparison of charge of cylinder used in 

 [Art. 539] with D + E. 



A thermometer tube whose length was 22-1 inc., weight = 2, 17, 21 and 

 weight water which filled bore 14 gra. was coated with tinfoil 15-5 long, conseq. 

 comp. power = * the spec. gra. of a part of the same tube being 3-243. 



Fr. Feb. 26 [1773]. Th. 52. N. 20 . 



The cyl. used in [Art. 539] compared with the plates D and E, the wire Mm 

 of machine being drawn out to 39^ inches, and resting on the cylinder as in 

 that experiment. A sliding trial plate on neg. side. 



[6 observations. See Art. 666.] 



546] Charge of second thermometer tube; also that of rosin plate with brass 

 coating; also that of A, B, and C laid on each other without coatings between. [10 

 observations. Art. 675.] 



The same things were tried the day before, Th. 55, N. 17^, but the wire for 

 making communication between machine and ground was forgot to be fixed. 

 [14 observations. See Art. 666.] 



547] f The quantity of electricity in plate D compared with that in a tin circle 

 of 36 and another 0/30 inches diameter by means of the machine used for comparing 

 simple plates J, the trial plate being a tin cylinder inches long, and in 

 circumference, fastened to the end of the usual sliding trial plates, with another 

 cylinder of the same size sliding within it. 



Tried with elect, of usual strength and with the middle sized corks. 

 Also the double plate A compared with the circle of i8J inc. 



* [So in MS.] t [Arts. 356, 664.] 



t [Art. 240.] [So in MS.] 



