506 A New Era in Illumination. [ Oct., 
Each of the sides of the electro-magnet is coiled with an insu- 
lated conductor, consisting of a bundle of seven No. 10 copper wires, 
laid parallel to each other, and bound together with a double cover- 
ing of linen tape. The length of conductor coiled round each side 
of the electro-magnet is 1,650 feet. T'wo of the extremities of the 
coils are connected together so as to form a continuous circuit 
3,300 feet in length; the other extremities of the coils terminate in 
the two insulated metal studs m m, fixed upon the wooden top of 
the machine, and connected thereby with the wires h h. The total 
weight of the two coils of insulated copper wire, without the iron, 
is half-a-ton. he diameter of the hole in the magnet cylinder is 
7 inches, and its length 35 inches. The separate parts of the 
cylinder are bolted together at the top and bottom by means of 
twelve copper bolts », three-quarters of an inch in diameter. The 
armature o, which is an exact. fac-simile, except as regards size, of 
the one already described, is about one-eighth of an inch less in 
diameter than the bore of the magnet cylinder. It is wound with 
an insulated strand of copper wire, 350 feet in length and a 
quarter of an inch in diameter, as shown in section in Fig. 3. A 
pulley d, 7 inches in diameter, is keyed upon one end of the armature, 
and upon the other end are fixed two hardened steel collars p, p', 
one of which is insulated from the armature axis. These form part 
of the commutator, by means of which the rapidly alternating 
currents are converted into an intermittent current moving in one 
direction only. These currents of electricity, which produce the — 
light, are taken from the steel collars by means of the springs q, q, 
and thence to the screw nuts at 7, from which they can be conveyed 
to any place required by the conductors s s. 
The armature of the 7-inch machine is driven at 1,800 revolu- 
tions per minute by means of the strap ¢, from the same shaft as 
the magneto-electric machine. Reservoirs for oil are shown at u. 
The total weight of the machine complete is a little more than 
1 ton. 
The action of the machine will be readily comprehended from 
the explanation previously given. The electricity induced from the 
permanent magnets a a a, in the rotating armature of the small 
machine is transmitted, by means of the wires h h, through the coils 
of the large electro-magnet of the 7-inch machine, the iron plates 
and magnet cylinder of which acquire an enormous amount of 
magnetism. Simultaneously a proportionately larger amount of 
electricity is induced in the wires of the larger armature, and this 
current of electricity is used for producing the light. When the 
machine is in full action, an engine of about three-horse power will 
be required to drive it, and the lamp will consume sticks of carbon 
at least 83-inch square. The power of the machine may be regu- 
lated according to the quantity of light required to suit the different 
