e rails further, holes are bored in them
on each side of the sleeper (see Fig. 42, c), and fine iron or, brass wire
is passed through these, round the bottom of the sleeper, and made fast.

[Illustration: FIG. 43.--Tin chair for centre rail of electric track.]

The centre rail is soldered to small tin chairs, the feet of which are
pinned down to the sleepers. The top of the rails must project slightly
above the chairs, so that the current collector may not be fouled.

Junctions.--At these points one 3/4-inch sleeper is reduced to 1/2-inch
width, and the other increased to 1 inch, this sleeper being overlapped 3/8
inch by the rails of the other section. To the outsides of the wheel rails
are soldered the little angle plates, AA, BB, attached to the sleepers by
brass tacks, which project sufficiently to take the brass wire hooks. These
hooks must be of the right length to pull upon the tacks in AA and make a
good contact. The centre rails are bonded by two strips of springy brass,
riveted to one section, and forced apart at their free end by the
interposed strip. Two pins projecting from the narrower sleeper fit into
holes in the wider to keep the sections in line at a junction.

General.--The sleepers of straight sections are screwed down to 3/4 by
1/4 inch longitudinals, which help to keep the track straight and prevent
the sleepers slipping. Sections should be of the same length and be
interchangeable. Make straight sections of the greatest convenient length,
to reduce the number of junctions. Sleepers need not be less than 6 inches
apart. Fix the sleepers on the longitudinals before hammering the rails
into the slots.

[Illustration: FIG. 44.--Laying out a curve for electric track.]

Curves.--A simple method of laying out a semi-circular curve is shown in
Fig. 44. Sleepers and longitudinals are replaced by 1/2-inch boards, 8
inches wide. Three pieces, about 32 inches long each, have their ends
bevelled off at an angle of 60 degrees, and are laid with their ends
touching. Two semi-circles of 24 and 22 inch radius are drawn on the boards
to indicate the positions of the rails, and short decapitated brass nails
are driven in on each side of a rail, about an inch apart, as it is laid
along one of these lines. (See Fig. 44. A.) The inside nails must not
project sufficiently to catch the wheel flanges. The spring of the brass
will prevent the rail falling out of place, but to make sure, it should be
tied in with wire at