pers. There are thus, at present, two systems of portable tracks:
those in which the sleepers are capable of being detached, and those in
which they are not so capable.

The portable track of the Decauville system is not capable of so coming
apart. The steel rails and sleepers are riveted together, and form only
one piece. The chief advantage of these railways is their great
firmness; besides this, since the line has only to be laid on the
surface just as it stands, there are not those costs of maintenance
which become unavoidable with lines of which the sleepers are fixed by
means of bolts, clamps, or other adjuncts, only too liable to be lost.
Moreover, tracks which are not capable of separation are lighter and
therefore more portable than those in which the sleepers are detachable.

With regard to sleepers, a distinction must be drawn between those which
project beyond the rails and those which do not so project. M.
Decauville has adopted the latter system, because it offers sufficient
strength, while the lines are lighter and less cumbersome. Where at
first he used flat iron sleepers, he now fits his lines with dished
steel sleepers, in accordance with Figs. 1 and 2.

[Illustration: Fig. 1. Fig. 2.]

This sleeper presents very great stiffness, at the same time preserving
its lightness; and the feature which specially distinguishes this
railway from others of the same class is not only its extreme strength,
but above all its solidity, which results from its bearing equally upon
the ground by means of the rail base and of the sleepers.

In special cases, M. Decauville provides also railroads with projecting
sleepers, whether of flat steel beaten out and rounded, or of channel
iron; but the sleeper and the rail are always inseparable, so as not to
lessen the strength, and also to facilitate the laying of the line. If
the ground is too soft, the railway is supported by bowl sleepers of
dished steel, Figs. 3 and 4, especially at the curves; but the necessity
for using these is but seldom experienced. The sleepers are riveted
cold. The rivets are of soft steel, and the pressure with which this
riveting is effected is so intense that the sleepers cannot be separated
from the rails, even after cutting off both heads of the rivets, unless
by heavy blows of the hammer, the rivets being driven so thoroughly into
the holes made in the rails and sleepers that they fill them up
completely.

The jointing of the rails is exce