FAST AND HEAVY RAILWAY SERVICE. 239
The character of the overhead structure in this part of
the line is well shown in Fig. 124. The greater neatness
and simplicity of the third rail arrangement is obvious.
Until this experiment fear of serious leakage has deterred
engineers from using such construction on ordinary road-
beds. A regular railroad construction with rails carried
YIG. 124.
on ties slightly above the surface of the ground is very
much less liable to leakage than street railway construc-
tion with nearly buried rails, particularly since in the
former the third rail can be supported on adequate insu-
lators.
Sesides this, an amount of leakage which would be
formidable in street railway work may be relatively quite
small in the heavy service of a suburban line. The third