of this success on subsequent development was negligible. Significant use
of electricity in this field occurred somewhat later, and in a manner
parallel to that by which steam was first applied to the elevator--the
driving of mechanical (belt driven) elevator machines by individual
motors. Slightly later came another application of the "conversion" type.
This was the simple substitution of electrically driven pumps (fig. 21)
for steam pumps in hydraulic installations. It will be recalled that pumps
were necessary in cases where water main pressure was insufficient to
operate the elevator directly.

In both of these cases the operational demands on the motor were of course
identical to those on the prime movers which they replaced; no reversal of
direction was necessary, the speed was constant, and the load was nearly
constant. Furthermore, the load could be applied to the motor gradually
through automatic relief valves on the pump and in the mechanical machines
by slippage as the belt was shifted from the loose to the fast pulleys.
The ultimate simplicity in control resulted from permitting the motor to
run continuously, drawing current only in proportion to its loading. The
direct-current motor of the 1880's was easily capable of such service, and
it was widely used in this way.

[Illustration: Figure 15.--Rope-geared hydraulic freight elevator using a
horizontal cylinder (about 1883). (From a Lane & Bodley illustrated
catalog of hydraulic elevators, Cincinnati, n.d.)]

[Illustration: Figure 16.--English direct plunger hydraulic elevator
(about 1895). (From F. Dye, _Popular Engineering_, London, 1895, p. 280.)]

Adaptation of the motor to the direct drive of an elevator machine was
quite another matter, the difficulties being largely those of control. At
this time the only practical means of starting a motor under load was by
introducing resistance into the circuit and cutting it out in a series of
steps as the speed picked up; precisely the method used to start traction
motors. In the early attempts to couple the motor directly to the winding
drum through worm gearing, this "notching up" was transmitted to the car
as a jerking motion, disagreeable to passengers and hard on machinery.
Furthermore, the controller contacts had a short life because of the
arcing which resulted from heavy starting currents. In all, such systems
were unsatisfactory and generally unreliable, and were held in disfavor by
both elevator e