* a . ~" ie * 
120 Contributions to Electricity and Magnetism. 
or fourth orders from the beginning induction, and its action was 
therefore supposed to be so feeble as not materially to affect the 
results obtained. 
. Subsequent reflection, however, led me to conclude, that in 
order to complete this part of my investigations, a more careful 
study ot th induction at the beginning of the current would be 
desirable, and accordingly, on resuming the experiments, my at- 
tention was first directed to the discovery of some means by 
which the intensity of this induction might be increased. After 
some preliminary experiments, it appeared probable that the de- 
sired result could be obtained by using a compound galvanic bat- 
tery, instead of the single one before employed. In reference to 
this conjecture the constant battery before mentioned (3) was 
constructed, and a series of experiments instituted with it, the 
results of which agreed with my anticipation. 
8. In the first experiment, coil No. 2, which it will be remem- 
bered (ILI, 7) consists of a copper riband of about sixty feet long, 
and coiled on itself like the main spring of a watch, was connec- 
ted with the compound battery, and helix No. 1, (IIL. 8,) formed 
of one thousand six hundred and sixty yards of fine copper wire, 
Fig. 3. ‘ 
7 7 
@ represents coil No. 1, 6 helix No. 1, and c, d, handles for receiving the shock. 
was placed on the coil to receive the induction, as is shown in 
figure 3, which is again inserted here for the convenience of the 
reader. This arrangement being made, currents of increasing 
intensity were passed through the coil, by constantly retaining 
one of its ends in the cup of mercury forming one extremity of 
the battery, and successively plunging the other end into the cups 
which served to form the connections of the several elements of 
the battery. With the current from one element, the shock at 
_ breaking the circuit was quite severe, but at making the same it 
was very feeble, and: ived in the fingers only of 
through the tongue. With two elements in the circuit, the shock 
* 
te 
