420 MR. DUGALD M‘KICHAN ON THE DETERMINATION OE THE NUMBER 
Temp. 9°-9°-7 C. March 16, 1870. Battery 180 cells. 
Resistance in B. A. 
v in centims. per 
second. 
Electrometer. 
Electrodynamometer. 
units. 1 = 10 9 centims. 
per second. 
Difference. 
Mean. 
Deflection. 
Mean. 
61-7 
61-8 
61-75 
R. 424-0 
L. 411-0 
417-5 
15342 
294-Ox 10 8 
6l*l 
60-7 
60-90 
R. 420-0 
L. 408-0 
414-0 
(15372) 
297*5 xlO 8 
61-3 
61-4 
61-35 
IE 419-5 
L. 407*0 
413-25 
(15402) 
295-6 x 10 8 
61-4 
61-1 
61-25 
R. 417*0 
L. 406-0 
411-5 
(15432) 
295-8 x 10 s 
61-3 
60-9 
61-10 
R. 416-0 
L. 413-0 
414-5 
(15462) 
298-4 x 10 s 
61-3 
61-2 
61-25 
R. 417*0 
L. 405-0 
411-0 
(15492) 
297-0 xlO 8 
61-5 
61-2 
61-35 
R. 417-5 
L. 408-0 
412-75 
15522 
297-7 x 10 8 
The resistance of the coils was measured at the beginning and at the end of this 
series. The intermediate values of the resistance are inserted on the supposition of a 
gradual increase in the resistance of the coils. 
The suspending-wire having been soldered to the brass cover to which it had been 
attached, the period of vibration of the coil was found to be 4'789 seconds; so that, for 
succeeding observations, y= ’000021884. 
At this stage an attempt was made to use simultaneous measurements made by means 
of the old and new absolute electrometers ; but this method was not carried out, chiefly 
on account of difficulties in the use of the old absolute electrometer arising from imper- 
fect insulation and other causes. The former method of comparison simply with the 
new absolute electrometer was resumed. 
Temp. 10 o, 8 C. March 22, 1870. Battery 180 cells. 
Electrometer. 
Electrodynamometer. 
Resistance in B. A. 
units. 1 = 10 9 centims. 
per second. 
v in centims. per 
second. 
Difference. 
61-15 
61-3 
61-1 
60-8 
Mean. 
61-22 
60-95 
Deflection. 
R. 391-25 
L. 391-5 
R. 389-5 
L. 390-0 
Mean. 
391-4 
389-25 
15654 
293- 6 x 10 8 
294- Ox 10 s 
I 
