e 
4 Charles Grafton Page. 
break in the circuit in the ities with which it eaters 
the current, is measurably proportional to the smallness of 
the number of plates into which the battery surface is divi- 
ed in series, with the volume of metal disposed in a length 
suitable thereto, eh that the intensity of the shock from the 
induction circuit, the — of the latter remaining unchanged, 
will in this way be in eased by reducing the length and inten-— 
ave of the battery drei Or, to state the same otherwise, if 
he spark formed by a break in ‘the induction circuit is to be of 
pale length (resistance) thee the short spark formed by the 
break in the battery circuit, the length of the induction circuit 
~ maust be in like ratio greater than that of the battery circuit ; and 
it is in this point of view that Prof. Page himself has stated the 
primary characteristic principle upon which the voltaic induc- 
tion coils depend for their effects. The step made by him in 1836, 
as above mentioned, was, so far as we are aware, the first step 
made in this direction. ‘An account of it was carried to Eu- 
rope by the late Francis Peabody of Salem, and communica- 
ted, rather imperfectly, to the English philosopher Sturgeon, 
in advance of its publication here. This communication 
would appear, by Sturgeon’s account, to have given the first 
impulse to a quite extensive series of ‘experiments made by the 
latter, and, within a year from the time of his interview with 
Peabody, he constructed an induction coil, described in the 
Annals of Electricity for Oct., 1837, vol. i, p. 477, in which the 
battery circuit agp of an inner helix of rather thick bell 
wire 260 fe ng, and the induction circuit of an outer helix 
of 1300 feet of very thin wire. This he = sometimes with, 
an without, an iron core in the common axis of 
the two relldtas and obtained strong shocks in either case. In 
the meantime, "however, Prof. Callan of Maynooth College, 
Treland, had been making ex experiments on an extensive scale, 
and had carried the multiplication of the length of the indue- 
tion circuit, as compared with that of the battery circuit, to 
a much greater extent than was done in the coil of Sturgeon, 
just noticed, and his results had been published in Sturgeon’ s 
Annals, But in his experiments he used the induction of very 
large solid masses of iron, and by overlooking the interference 
of the electric currents that must be induced in the solid me- 
tallic mass of the electro-magnet, he was prevented from di 
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