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 distance of two miles. The present system when finished will comprise about twenty miles of single track or ten miles of double track tunnels.

All the latest devices in the construction and operation of the system are used. The trains are run on the third rail system and the cars are made entirely of steel and are absolutely fire-proof. The doors of the cars are operated by compressed air, and are automatically adjusted so that the electric signal to start the train cannot be given until every door is closed. There are also automatic devices for stopping the train in emergencies.

The great terminal building at Cortlandt street, New York, is almost as great an engineering triumph as the tunnels. The combination of office buildings and railroad terminal was an idea original with the tunnel company and has been worked out on a gigantic scale, with many unique and remarkable features. It really consists of two buildings, each covering an entire block, and connected by a bridge over the intervening street. The building is twenty-two stories above the street and four stories below, and is probably the largest office building in the world. It will accommodate 10,000 persons. The construction is of solid steel, 28,000 tons being used, and the total cost was over $13,000,000. Its erection was a remarkable feat of engineering. Soon after starting to dig for the foundation a bed of quicksand was encountered. Before the foundation could be laid it was found necessary to sink an immense cofferdam inclosing the entire space for two square blocks. The space inside of this was excavated to a depth of nearly one hundred feet to the bed rock on which the caisons and concrete foundations of the building were placed. The terminal station for the tunnels is in this building about thirty feet below the street level, and connections can be made here with the subway and elevated roads and there is also a passage leading to Broadway. The ticket offices, baggage and similar rooms are on the next floor; and on the street level the office floors of the building commence.

The thanks of the Trustees of the Free Public Library are due to Mr. William G. McAdoo of the Hudson and Manhattan Railroad Company and to Mr. F. L. Sheppard of the Pennsylvania Railroad Company for information furnished; and to Edmund W. Miller, Secretary of the Public Library, for the compilation of the foregoing paper. Rh