With this description of railway it does not matter whether the curves are to the right or to the left.  The pair of rails are curved to a suitable radius, and can only need turning end for end to form a curve in the direction required.  The rails weigh 9 lb., 14 lb., 19 lb., and 24 lb. per running yard, and are very similar to the rails used on the main railways of France, except that their base has a proportionally greater width.  As to the strength of the rail, it is much greater in proportion to the load than would at first sight be thought; all narrow-gauge railways being formed on the principle of distributing the load over a large number of axles, and so reducing the amount on each wheel.  For instance, the 9 lb. rail used for the portable railway easily bears a weight of half a ton for each pair of wheels.

The distance between the rails differs according to the purpose for which they are intended.  The most usual gauges are 16in., 20 in., and 24in.  The line of 16 in. gauge, with 9 lb. rails, although extremely light, is used very successfully in farming, and in the interior of workshops.

[Illustration:  Fig. 3.  Fig. 4.  Fig. 5.]

A length of 16 ft. 5 in. of 9 lb. steel rail, to 16 in. gauge, with sleepers, etc., scarcely weighs more than 1 cwt., and may therefore be readily carried by a man placing himself in the middle and taking a rail in each hand.

Those members of the Institution who recently visited the new port of Antwerp will recollect having seen there the portable railway which Messrs. Couvreux and Hersetit had in use; and as it was these works at the port of Antwerp that gave rise to the idea of this paper, it will be well to begin with a description of this style of contractor’s plant.

The earth in such works may be shifted by hand, horsepower, or locomotive.  For small works the railway of 16 in. gauge, with the 9 lb. rails, is commonly used, and the trucks carry double equilibrium tipping-boxes, containing 9 to 11 cubic feet.  These wagons, having tipping-boxes without any mechanical appliances, are very serviceable; since the box, having neither door nor hinge, is not liable to need repairs.

This box keeps perfectly in equilibrium upon the most broken up roads.  To tip it up to the right or the left, it must simply be pushed from the opposite side, and the contents are at once emptied clean out.  In order that the bodies of the wagons may not touch at the top, when several are coupled together, each end of the wagon is furnished with a buffer, composed of a flat iron bar cranked, and furnished with a hanging hook.

Plant of this description is now being used in an important English undertaking at the port of Newhaven, where it is employed not only on the earthworks, but also for transporting the concrete manufactured with Mr. Carey’s special concrete machine.