quick, even those in the "pass-bies," I thought it expedient to employ
differential gear, as illustrated at D, Fig. 1, which is a sketch plan
showing the mechanism employed. M is a Siemens electric motor running at
650 revolutions per minute; E is a combination of box gearing, frictional
clutch, and chain pinion, and from this pinion a steel chain passes around
the chain-wheel, H, which is free to revolve upon the axle, and carries
within it the differential pinion, gearing with the bevel-wheel, B², keyed
upon the sleeve of the loose tram-wheel, T², and with the bevel-wheel, B¹,
keyed upon the axle, to which the other tram-wheel, T¹, is attached. To the
other tram-wheels no gear is connected; one of them is fast to the axle,
and the other runs loose, but to them the brake is applied in the usual
manner.

The electric current from the collector passes, by means of a copper wire,
and a switch upon the dashboard of the car, and resistance coils placed
under the seats, to the motor, and from the motor by means of an adjustable
clip (illustrated in diagram, Fig. 2) to the axles, and by them through the
four wheels to the rails, which form the return circuit.

[Illustration: FIG. 3]

I have designed many modifications of the track, but it is, perhaps, best
at present to describe only that which I have in actual use, and it is
illustrated in diagram, Fig. 3, which is a sectional and perspective view
of the central channel. L is the surface of the road, and SS are the
sleepers, CC are the chairs which hold the angle iron, AA forming the
longitudinally slotted center rail and the electric lead, which consists of
two half-tubes of copper insulated from the chairs by the blocks, I, I. A
special brass clamp, free to slide upon the tube, is employed for this
purpose, and the same form of clamp serves to join the two ends of the