the reservoir, and the energy thus stored must be rendered available
for re-starting the train. Trials in this direction have been made
through the application of strong springs which are caused to engage
upon the wheels when the brake is applied, and thus are wound up, but
which may then be reversed in position, so that for the starting of
the vehicle the rebound of the spring offers material assistance. It
is obvious, however, that the use of compressed air harmonises better
with the railway system than any plan depending upon springs. The
potential elasticity in an air-reservoir of portable dimensions is
enormously greater than that of any metallic spring which could
conveniently be carried.

In picking up and setting down mail-bags a system has been for some
years in operation on certain railway lines indicating in a small way
the possibilities of the future in the direction of obviating the need
for stopping trains at stations. The bag is hung on a sliding rod
outside of the platform, and on a corresponding part of the van is
affixed a strong net, which comes in contact with the bag and catches
it while the train goes past at full speed. Dropping a bag is, of
course, a simpler matter.

The occasionally urgent demand for the sending of parcels in a similar
manner has set many inventive brains to work on the problem of
extending the possibilities of this system, and there seems no reason
to doubt that before long it will be practicable to load some classes
of small, and not readily broken, articles into trucks or vans while
trains are in motion.

The root idea from which such an invention will spring may be borrowed
from the sliding rail and tobogganing devices already introduced in
pleasure grounds for the amusement of those who enjoy trying every
novel excitement. A light and very small truck may be caused to run
down an incline and to throw itself into one of the trucks comprising
a goods train. The method of timing the descent, of course, will only
be definitely ascertained after careful calculation and experiments
designed to determine what length of time must elapse between the
liberation of the small descending truck and the passing of the
vehicle into which its contents are to be projected.

Foot-bridges over railway lines at wayside stations will afford the
first conveniences to serve as tentative appliances for the purpose
indicated. From the overway of the bridge are built out two light
frameworks ca