i 
8 Charles Grafton Page. 
ago. It was, however, similar in its general construction to 
the last mentioned machine, except that the helices around the 
rotating armatures were ‘“‘ made up of a series of copper discs, 
instead of wires, each disc being split, and one of its split 
edges joined to the edges of the adjoining disc.” Prof. Pag 
as also informed us (History of Induction, p. 124), that “ the 
ate magnets weighed about sixty pounds each, and when first 
charged would each sustain its own weight,” and that “ the 
combined lifting power was not at any time more than one 
hundred and thirty pounds.” It is obvious that ‘the length of 
conductor in the helix of this construction was comparatively 
small. Of the length and size of the wire that surrounded 
the electro-magnet of one thousand pains we find no direct 
information. But that the length was far greater than the 
virtual length of the rotating armature helices of the machine 
is fairly deducible, we think, from the result. The current in- 
duced in the rotating armature helix must be generated in a 
half revolution, and the limit which is set to its quantity by 
its induction upon itself, and by its reaction upon the magnet- 
ization of the armature, is the same for all velocities of rota- 
tion however great. ut if a resistance interposed between 
the terminals of the helix prevent the current from reaching 
that limit of quantity, the electro-motive force with which it 
will break through that resistance may be increased indefinitely 
by increasing the velocity of revolution. Hence, an outside 
wire joining the terminals of the helix, provided only the cur- 
rents of the helix are discharged, by means of a pole-changer, 
in one constant direction pi see this outside wire, so that 
there is no induction in it of the current upon itself, may have 
its length greatly multiplied aie that of the helix conduc- 
tor, without any proportionate reduction in the oS to 
which the current is at any rate limited. Hence the powe 
electro-magnet that can be produced by forming this length- 
_ ened outside wire into a coil around an iron bar, Admitting 
that this must be, in fact, the principle of action to which 
Prof. Page resorted in producing an electro-magnet of a sus- 
taining power of 1,000 pounds, from magnets whose united 
sustaining power was not over 125 or 130 pounds, we have in 
this result one main element of the recent famous Wilde ma- 
O- 
The “ History of Induction,” to which we 9, wa referred 
above, a work of 124 octavo pages, was written by Prof. Page 
we the last year of his life, while laboring under his fatal mal- 
ady, and contains a detailed history of oa and inven- 
tion relative to this branch of electrical science 
