244 
PROFESSOR TYNDALL’S FURTHER RESEARCHES 
Wishing to place myself beyond the possibility of illusion as regards the fact of 
deflection, I repeated the experiment with successive batteries of two, three and four 
cells. The following are the results 
II. 
2 cells. 
3 cells. 
4 cells. 
Position 1. 
460 
439 
425 
Position 2. 
462 
450 
437 
Position 3. 
473 
462 
448 
In all the cases cited we observe the same result. From position 2 to position 1 
the motion is from larger to smaller numbers ; while from position 2 to position 3 
the motion is from smaller to larger numbers. 
It may at first sight appear strange that the amount of the deflection did not increase 
with the battery power ; the reason, in part, is that the magnet, when the current 
circulated, was held in a position free from the spirals, by forces emanating partly 
from the latter and partly from a portion of the external circuit. When the current 
increased, the magnetization of the bismuth increased also, but so did the force which 
held the magnets in their position of equilibrium. To remove them from this posi- 
tion, a greater amount of force was necessary than when only the residual action of a 
feeble current held them there. This fact, coupled with the circumstance that less 
heat was developed, and less disturbance caused by air currents, when a feeble bat- 
tery was used, induced me for some time to experiment with a battery of two cells. 
Subsequent experience however enabled me to change this for five cells with advan- 
tage. 
Notwithstanding the improbability of the argument, still it may be urged that 
these experiments do not prove beyond a doubt that the bismuth cylinders produce 
the motion of the magnets in virtue of their excitement by the voltaic current ; for it 
is not certain that these cylinders would not produce the same motion wholly inde- 
pendent of the current. Something of this kind has occurred to M. Leyser* in his 
experiments, and why not here ? 
In answer to this I reply, that if the case be as here suggested, the motion of the 
magnet will not be changed when the current surrounding the bismuth cylinders 
flows in the opposite direction. Here is the experiment. 
III. 
Position 1. 764 
Position 2. 742 
Position 3. 704 
We observe here that in passing from position 2 to position 1 the motion is from 
smaller to larger numbers ; while in passing from position 2 to position 3 the motion 
* Scientific Memoirs, New Series, vol. i. page 184. 
