sie 
On Electro-Dynamic Induction. 139 
nomena. And, first, however varied may be the intensity of the 
induction expressed by the different parts of the two ends of the 
curve, we may immediately infer that a galvanometer, placed in 
the circuit of the secondary conductor, will be equally affected 
at the beginning and ending of the primary current; for, since 
the deflection of this instrument is due to the whole amount of 
a current, whatever may be its intensity, (57,) and since the or- 
dinates cB and Cd are equal, which represent the quantity of in- 
duction in the two directions, and, consequently, the amount o 
the secondary current, therefore the deflection at the beginni 
and ending of the battery current will, in all cases, be 
nal. 
This inference is in strict accordance with the results of experi- 
ment ; for, however rapidly or slowly we may plunge the battery 
into the acid, and however irregular may be the rate at which it 
is drawn out, still, if the whole effect be produced within the 
time of one swing of the needle, the galvanometer is deflected to 
an equal degree. | : 
_ 66. Again, the intensity of one part of the inductive action, 
for example that represented by Ag, may be supposed to be so 
great as to produce a secondary current capable of penetrating the 
body, and of thus producing a shock* while the other parts of the 
action, represented by gB and CD, are so feeble as to affect the 
galvanometer only. We would then have a result the same as 
one of those given in the last section, (42,) and which was sup- 
posed to be produced by two kinds of induction ; for if the shock 
Were referred to as the test of the existence of an induced cur- 
rent, one would be found at the beginning only of the battery 
current, while, if the galvanometer were consulted, we would 
perceive the effects of a current as powerful at the ending as at 
the beginning. 
67. The results mentioned in the last paragraph cannot be 
obtained by plunging a battery into the acid; the formation of 
the current in this way is not sufficiently rapid to produce a shock. 
The example was given to illustrate the manner In which the 
same effect is supposed to be produced, in the case of the more 
sudden formation of a current, by plunging one end of the conduc- 
tor into a cup of mercury permanently attached to a battery already 
Pon re ae 
* The shock depends more on the intensity than on the quantity. See para- 
graph 13. 
