‘ On the Galvanic Current. : 87 
gvith 
: manifested in the circuit, but that the entire current passe 
all its intensity.” Prof. Henry, however, in his valuable paper 
on electro-dynamic induction, published in 1840, takes ‘the more 
consistent ground as follows. He remarks that, “rapid as may __ 
e the development of the current, it cannot be supposed to as-..~ 
sume per saltum, its maximum state of quantity; on the contra- — 
ry, from the general law of continuity, we would infer that it 
passes through all the intermediate states of quantity, from that 
of no current, if the expression may be allowed, to one of full 
development; there are however, considerations of an experi- 
mental nature, which would lead us to the same conclusion, and 
also to the further inference that the decline of the current is not 
instantaneous.” Prof. Henry also inferred that the “ time of the 
subsidence of the current when the circuit is broken by means 
results lead to conclusions differing from those of Henry only with 
the rise of the current as well as its subsidence, and that the time 
of subsidence is the same as that of the rise of the current, and 
that both depend upon the force of the induced current. The 
induced current ceteris paribus depends upon the figure, size and 
construction of the coil, and therefore, the rise and subsidence of 
the current is governed as to its time, chiefly by the configura- — 
tion and size of the coil. 
spark was small, 
of contact, the 
d in volume and 
sound. It was not difficult by the aid of a metronome, to time 
_ the contact and to ascertain with some accuracy the time required 
_ to give the spark its full effect. : 
_ On connecting two, three, or more coils with the same battery, 
the result was much more striking, from the fact that the 
