Puslapio vaizdai
[graphic][merged small]
[blocks in formation]

HERE are one hundred and fifty thousand

miles of railway in the United States : three hundred thousand miles of rails—in length enough to make twelve steel girdles for the earth's circumference. This enormous length of rail is wonderful—we do not really grasp its significance. But the rail itself, the little section of steel, is an engineering feat. The change of its form from the curious and clumsy iron pear-head of thirty years ago to the present refined section of steel is a scientific development. It is now a beam whose every dimen

sion and curve and angle are exactly suited to the tremendous work it has to do. The loads it carries are enormous, the blows it receives are heavy and constant, but it carries the loads and bears the blows and does its duty. The locomotive and the modern passenger and freight cars are great achievements; and so is the little rail which carries them all.

The railway to-day is one of the matter-of-fact associations of our active life. We use it so constantly that it requires some little effort to think of it as a wonderful thing; a creation of man's ingenuity, which did not exist when our grandfathers were young. Its long bridges, high viaducts, dark tunnels may be remarked and remembered by the traveller, but the narrow way of steel, the road itself, seems but a simple work. And yet the problem of location, the determination, foot by foot and mile by mile, of where the line must go, calls in its successful solution for the highest skill of the engineer, whose profession before the railway was created hardly existed at all. Locomotives now climb heights which a few years ago no vehicle on wheels could ascend. The writer, with some engineer friends, was in the mountains of Colorado last year, and saw a train of very intelligent donkeys loaded with ore from the mines, to which no access could be had but by those sure-footed beasts. And since then one of that party of engineers has located and is building a railway to those very mines. No heights seem too great to-day, no valleys too deep, no cañons too forbidding, no streams too wide. If commerce demands, the engineer will respond and the railway will be built.

The location of the line of a railway through difficult country requires the trained judgment of an engineer of special experience, and the most difficult country is not by any means that which might at first be supposed. A line through a narrow pass almost locates itself. But the approach to a summit

Copyright, 1888, by Charles Scribner's Sons. All rights reserved.


through rolling country is often a serious problem. The rate of grade must be kept as light as possible and must never exceed the prescribed maximum. The cuttings and the embankments must be as shallow as they can be made-the quantities of material taken from the excavations should be just about enough to make adjacent embankments. The curves must be few and of light radius-never exceeding an arranged limit. The line must always be kept as direct as these considerations will allow—so that the final location will give the shortest practicable, economical distance from point to point. Many a mile of railway over which we View Down the Blue from Rocky Point; Denver, South Park travel now at the highest speed, has been

and Pacific Railroad; showing successive tiers of railway. a weary problem to the engineer of location, and he has often accomplished a than if he had with apparent boldness really greater success by securing a line cut deep into the hills and raised emwhich seems to closely fit the country bankments and viaducts high over lowover which it runs without marking it- lands and valleys. self sharply upon nature's moulding, But roads must run through many

« AnkstesnisTęsti »