[Illustration: Making an Embankment.] The works are then let, either to one large contractor or to several smaller ones, and the labor of construction begins. The duties of the engineers are to stake out the work for the contractors, make monthly returns of its progress, and see that it is well done and according to the specifications and contract. The line is divided into sections, and an engineer, with his assistants, is placed in charge of each. Where the works are heavy, the contractors build shanties for their men and teams near the heavy cuttings or embankments. It is the custom to take out heavy cuttings by means of the machine called a steam shovel, which will dig as many yards in a day as 500 men. [Illustration: Steam Excavator.] On the prairies of the West the road-bed is thrown up from ditches on each side, either by men with wheelbarrows and carts, or by means of a ditching-machine, which can move 3,000 yards of earth daily. In this case the track follows immediately after the embankment, and the men live in cars fitted up as boarding-shanties, and moved forward as fast as required. If the country contains suitable stone, the culverts and bridge abutments are built by gangs of masons and stone-cutters, who move from point to point. But the general practice is to put in temporary trestle-work of timber resting upon piles, which trestle-work is renewed in the shape of stone culverts covered by embankments, or iron bridges resting on stone abutments and built after the road is running. [Illustration: Building a Culvert.] [Illustration] The pile-driver plays a very important part therefore in the construction of our railroads, and has been brought to great perfection. It is worked by a small boiler and engine, and gives its blows with great rapidity. It drags the piles up to leaders and lifts them into place by steam-power, so that it is worked by a small gang of men. Finally, it is as portable as a pedler's cart, and as soon as it has finished one job it is taken to pieces, packed upon wagons, and moved on to the next job. [Illustration: (Rock Drill.)] Tunnels are neither so long nor so frequent upon American railways as upon those of Europe. The longest are from two to two and a half miles long, except one, the Hoosac, about four miles. Sometimes they are unavoidable. The ridge called Bergen Hill, west of Hoboken, N. J., is a case in point. This is pierced by the tunnels of the West Shore, of the Delaware, Lackawanna, and Western, and of the Erie, the last two of which, as shown on page 25, are placed at different levels to enable one road to pass over the other. [Illustration: Rock Drill.]