THE POPULAR SCIENCE MONTHLY.
|ECONOMY OF RAILWAY LOCOMOTION.|
By J. W. GROVER, C.E.
THE primary conception of a railway is a perfectly smooth, level, and straight road, upon which friction is reduced to the minimum, so that heavy loads may be propelled with the least possible resistance, and at the highest rate of speed.
The earliest type of locomotive-engine was designed to run upon such straight and level roads, and it was supposed for many years that locomotives could not climb hills, or be made to go round corners.
The first railway-carriages were a simple modification of the stage-coaches, names and all. It is interesting to look at the curious three-bodied "Marquis of Stafford"—with yellow panels and windows, filled with ladies in large coal-scuttle bonnets—as shown in one of Ackermann's early engravings of the Liverpool and Manchester Railway, the only substantial difference being that, inasmuch as the railways of those days were made nearly straight, no arrangement was provided for allowing the axles of the carriage to radiate as they do partially in common road-vehicles, but both axles were rigidly fastened so as to be immovable.
Again, as all road-vehicles have to turn abrupt corners, their wheels are made to turn independently upon their axles, but, so soon as flanges were employed to keep the wheels of the railway-carriages between two straight rails, this arrangement was found unnecessary, and, to obtain greater strength and security, the wheels were rigidly fastened to the axle, and both were compelled to revolve together.
Now, since the primary conception of the perfectly smooth, straight road, a great degeneracy has been of necessity taking place; with greatly increased demands, less capital than ever has been forthcoming; consequently the great cuttings and embankments of early days are being abandoned as precedents, and it becomes necessary that railways should approach more closely to the form of ordinary roads, which follow the surface of the ground only, at small cost.
Hence it follows that the rolling-stock itself must revert more nearly to its original pattern, readopting those contrivances which, under altered circumstances, were discarded.
Let us keep to the most elementary principles, for it is these which are forgotten and misunderstood, and yet should be engraven on brass and hung up in every railway board-room in the world. On a common road, a horse can pull a ton weight in a cart behind him on the level at 4 to 4¼ miles an hour, or, which is the same thing, if a weight of 70 lbs. were hung over a pulley and lowered down a well, he could pull it up at the speed mentioned. It is necessary to be a