ME. LATIMEE CLAEK ON A STANDAED VOLTAIC BATTEEY. 
11 
It is not necessary to give the mathematical formula used in calculating the values of 
E, but the following Table gives the results of the whole of the series of observations 
with the electrodynamometer. 
Date. 
Yalue of E in volts. 
Remarks. 
8 
December 1871 ... 
1-4585 
3 cells. 
9 
„ 99 
1-4651 
3 cells. 
14 
1-4616 
3 cells. 
15 
1-4561 
3 cells. 
15 
99 99 
1-4579 
2 cells. 
16 
99 99 
1-4586 
3 cells. 
„ 
1-4517 
3 cells, coil turned 180°. 
„ 
1-4552 
2 cells, coil turned back 1 80°. 
„ 
99 99 
1-4565 
3 cells. 
J5 
1-4535 
2 cells. 
1-4564 
3 cells. 
18 
99 99 
1-4649 
3 cells. 
19 
1-4562 
3 cells, coil turned 180°. 
„ 
1-4558 
3 cells, coil turned back 180°. 
20 
99 99 
1-4615 
3 cells. 
„ 
1-4539 
3 cells. 
,, 
1-4551 
2 cells. 
21 
» 
1-4549 
3 cells. 
Mean value of E 
1-45735 volt. 
Temperature 15°-5 Cent. 
The cells were frequently changed during the course of the experiments. Values 
were also obtained when the suspended coil was moved two millims. in various directions 
about the centre, but they did not differ sensibly from the above. 
As a verification of the results obtained with the electrodynamometer, the electro- 
motive force of the new element was also determined by means of the sine galvano- 
meter by a method which is well known, viz. 
E =(^ Hsinfl ) xE ’ (3) 
where E is the electromotive force, K is the radius of the circle, n the number of turns, 
H the horizontal intensity of the earth’s magnetism, 6 the angle through which the coils 
must be turned in order to maintain the needle in the plane of the coils, and R the 
resistance of the circuit in absolute measure. 
The instrument employed was specially constructed for these experiments, and presents 
some novelties. The needle was one centimetre in length, and was furnished with a 
mirror of parallel glass silvered by the chemical process, so that the reflection from either 
side could be observed in the telescope. The coil was 140 millimetres in diameter, and 
was furnished with a large mirror accurately parallel to its plane, silvered on the observing 
or front side, and having the centre of the coil marked upon it ; by the aid of the tele" 
scope and these mirrors it was easy to adjust the needle accurately to the centre of the 
coil, and to ensure that the plane of the coil was truly vertical, and coincided with the 
magnetic meridian. 
The telescope was carried on an arm one metre in length, which with the coil turned 
c 2 
