By
moving the lever along the coil the amount of German silver wire, which
offers resistance to the current, is altered. When starting the motor use
as little current as possible, and open the resistance as it gets up speed,
choking down again when the necessary speed is attained.
General.--All the three fittings described should for convenience be
mounted on the same board, which itself may form the cover of the box
holding the dry cells or accumulators.
SOME SUGGESTIONS.
Instead of dry cells or accumulators a small foot or hand operated dynamo
generating direct, not alternating current, might be used. Its life is
indefinitely long, whereas dry cells become exhausted with use, and
accumulators need recharging from time to time. On occasion such a dynamo
might prove very convenient.
Anyone who possesses a fair-sized stationary engine and boiler might
increase the realism of the outdoor track by setting up a generating
station, which will give a good deal of extra fun.
XIV. A SIMPLE RECIPROCATING ENGINE.
Figs. 51 and 52 illustrate a very simple form of fixed-cylinder engine
controlled by a slide valve.
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