cribed above can easily be repaired
in a few minutes without requiring any skilled workman.

The narrow-gauge system, which has recently received so great a
development on the Continent, since its usefulness has been
demonstrated, and the facility with which it can be applied to the most
varied purposes, has not yet met in England with the same universal
acceptance; and those members of this Institution who crossed the sea to
go to Belgium were, perhaps, surprised to see so large a number of
portable railways employed for agricultural and building purposes and
for contractors' works. But in the hands of so practical a people it may
be expected that the portable narrow gauge railway will soon be applied
even to a larger number of purposes than is the case elsewhere.

* * * * *

GERARD'S ALTERNATING CURRENT MACHINE.

The machine represented in the annexed engravings consists of a movable
inductor, whose alternate poles pass in front of an armature composed of
a double number of oblong and flat bobbins, that are affixed to a circle
firmly connected with the frame. There is a similar circle on each side
of the inductor. The armature is stationary, and the wires that start
from the bobbins are connected with terminals placed upon a wooden
support that surmounts the machine.

[Illustration: GERARD'S ALTERNATING ELECTRIC MACHINE.]

This arrangement allows of every possible grouping of the currents
according to requirements. Thus, the armature may be divided into two
currents, so as to allow of carbons 30 mm. in diameter being burned, or
else so as to have four, eight, twelve, twenty-four, or even forty-eight
distinct circuits capable of being used altogether or in part.

This machine has been studied with a view of rendering the lamps
independent; and there may be produced with it, for example, a voltaic
arc of an intensity of from 250 to 600 carcels for the lighting of a
courtyard, or it may be used for producing arcs of less intensity for
shops, or for supplying incandescent lamps. As each of the circuits is
independent, it becomes easy to light or extinguish any one of the lamps
at will. Since the conductors are formed of ordinary simple wires, the
cost attending the installation of 12 or 24 lamps amounts to just about
the same as it would in the case of a single cable.

[Illustration: GERARD'S 250 H.P. DIRECT CONNECTION ALTERNATING CURRENT
STEAM DYNAMO-ELECTRIC MACHINE.]

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