It is all new and wonderful, blazing this path for civilization; sometimes it is even accidental. An engineer, baffled to find a crossing over the Rockies for a transcontinental route saw an eagle disappear through a cleft in the hills that his eye had not before detected. He followed the course of the eagle; to-day the rails of the transcontinental reach through that cleft, and the time-table shows it as Eagle Pass.
Possibly there are still alternative routes when the surveyers return in the fall and begin to make their finished drawings. Final choices must now be made, and land-maps that show the property that the railroad will have to acquire, prepared. The details, of infinite number, are being worked out with infinite care.
The great problem of all is the problem of grades; in a mountainous stretch of line this is almost the entire problem. Obviously a perfect stretch of railroad would be straight and without grades. The railroad that comes nearest that practically impossible standard comes nearest to perfection. But as it comes near this perfection, the cost of construction multiplies many times. Most new lines must feel their way carefully at the outset. Moreover it is not an impossible thing to reconstruct it after years of affluence--of which more in another chapter.
A three-per-cent grade is almost the extreme limit for anything like a profitable operation; even a two-per-cent grade is one in which the operating people look forward to reconstruction and elimination. Yet there are short lengths of line up in the mining camps of Colorado, where grades of more than four per cent are operated; and it is a matter of railroad history that away back in 1852, when the Baltimore & Ohio Railroad was being pushed through toward Parkersburg, and the great Kingwood tunnel was being dug, B. H. Latrobe, the chief engineer of the company, built and successfully operated a temporary line over the divide at a grade of ten per cent--528 feet to the mile. A locomotive which weighed 28 tons on its driving-wheels carried a single passenger car, weighing 15 tons, in safety and in regular operation over this stupendous grade for more than six months. The ascent was made by means of zigzag tracks on the so-called switchback principle. That scheme succeeded earlier planes operated by endless chains; an instance of which is the quite famous road of Mauch Chunk, originally operated for coal, and now a side scenic trip for passengers. Other planes of this sort, you will remember, were in operation at Albany and Schenectady on the old Mohawk & Hudson route, now a part of the New York Central lines; but all of them involved a change of passengers and freight to and from their cars, and the zigzag switchback was considered quite an advance in its day. Two of these ancient switchbacks are still in regular use for passengers and freight--one at Honesdale, Pa., and the other at Ithaca, N. Y.