with 14 lb. rails, thirty basket wagons, and accessories for the
transport of sugar cane, is 700l., and the total weight of this plant
amounts to 35 tons.

Owing to the great lightness of the portable railways, and the facility
with which they can be worked, the attention of explorers has repeatedly
been attracted by them. The expedition of the Ogowe in October, 1880,
that of the Upper Congo in November, 1881, and the Congo mission under
Savorgnan de Brazza, have all made use of the Decauville narrow-gauge
railway system.

During these expeditions to Central Africa, one of the greatest
obstacles to be surmounted was the transport of boats where the river
ceased to be navigable; for it was then necessary to employ a great
number of negroes for carrying both the boats and the luggage. The
explorers were, more or less, left to the mercy of the natives, and but
very slow progress could be made.

On returning from one of these expeditions in Africa, Dr. Balay and M.
Mizon conceived the idea of applying to M. Decauville for advice as to
whether the narrow-gauge line might not be profitably adapted for the
expedition. M. Decauville proposed to them to transport their boats
without taking them to pieces, or unloading them, by placing them on two
pivot trollies, in the same manner as the guns are transported in
fortifications and in the field. The first experiments were made at
Petit-Bourg with a pleasure yacht. The hull, weighing 4 tons, was placed
on two gun trollies, and was moved about easily across country by means
of a portable line of 20 in. gauge, with 14 lb. rails. The length of the
hull was about 45 ft., depth 6 ft. 7 in., and breadth of beam 8 ft. 2
in., that is to say, five times the width of the narrow-gauge, and