1866. | Wilde’s Magneto-electric Machine. 505 
iron, and cc brass, and it is so arranged that b b, being screwed 
on to the respective poles of the magnets at d, form one entire north 
pole and one entire south pole to the 16 magnets, separated from each 
other by the brass pieces «. A circular hole, 24 inches in diameter, 
is bored lengthways through the metals, so as to form them into 
a hollow cylinder of brass and iron. Fig. 4 represents the armature ; 
a transverse section of which is also shown in its place inside the 
hollow cylinder, Fig. 3. It consists of a cylinder of cast-iron, about 
one-twentieth of an inch less in diameter than the hole in the 
cylinder b, c, b, ¢, so that it may revolve in very close proximity to 
the interior of the hollow cylinder without touching it; being held 
at each end by appropriate brass supports, in which the axis of the 
cylinder works. At one end of the armature is a cylindrical pro- 
longation d, on which a pulley e works, and at the other end is 
fixed acommutator. About fifty feet of insulated copper wire, one- 
eighth of an inch in diameter, are wound upon the armature in the 
direction of its length, as shown in Fig. 4, and in section in Fig. 3. 
The inner extremity of the wire is fixed in good metallic contact 
with the armature, the other end being connected with the insulated 
half of the commutator. Bands of sheet brass, ff, are bound at 
intervals round the armature, in grooves sunk in it for that pur- 
pose, their object being to prevent the convolutions of insulated 
wire from flying out of position by centrifugal force when in rapid 
rotation. 
By means of the small strap e, the armature is made to revolve 
in the interior of the magnet-cylinder at about 2,500 revolutions per 
minute. During each revolution, two waves of.electricity, moving 
in opposite directions, are induced in the insulated copper wire 
surrounding the armature. The rapid succession of alternating 
wayes thus generated at the rate of 5,000 per minute are, by means 
of the commutator at g, converted into an intermittent current 
moving in one direction only, which is conducted along the wires h. 
The electro-magnetic machine by which the light is produced is 
of precisely the same construction as the magneto-electric machine 
just described, except that an electro-magnet ¢ is substituted for the 
permanent magnets a, a. The electro-magnet 7, Figs. 1 and 2, is 
formed of two rectangular plates j, of rolled iron, 36 inches in 
length, 26 inches in width, and 1 inch in thickness, as shown by 
the dotted lines. They are bolted, parallel with each other, to the 
sides of the magnet cylinder & by means of the bolts 7, and the 
plates are connected together at their upper extremities, by being 
bolted to a bridge formed of two thicknesses of the same iron as 
that of which the sides are made. All the component parts of the 
electro-magnet, requiring to be fitted together and to the magnet 
cylinder, are planed to a true surface, for the purpose of ensuring 
intimate metallic contact throughout the entire mass. 
