Before this original section of the subway was completed it already was in process of extension toward the south; from the City Hall to and under the South Ferry to Brooklyn which it reached in two successive leaps; the first to the Borough Hall (the old Brooklyn City Hall) and the second to the Atlantic Avenue station of the Long Island Railroad, which has remained its terminus until within the past twelvemonth. More recently the original subway system of Greater New York has been so changed and enlarged as to all but lose sight of the original plan. Instead of a single main-stem up the backbone of New York, there are now two parallel trunks--the one on the east side of the town and the other upon the west--and the now isolated link of the original main line in Forty-second Street has become a shuttle service from the Grand Central Station to Times Square and the crossbar of the letter "H" which forms the rough plan of the entire system. Still other underground railroads have come to supplement the vast task of this original system. It is more than a decade since the energy of William G. McAdoo completed the Hudson River Tubes, which an earlier generation had had the vision but not the ability to build, and brought their upper stem through and under Sixth Avenue and to a terminal at Herald Square; while even more recently the huge and far-reaching Brooklyn Rapid Transit system has appropriated Broadway, Manhattan, for a vastly elongated terminal; which takes the concrete form of a four-tracked underground railroad beneath that world-famed street all the way from the City Hall to Times Square and above that point through Seventh Avenue to Fifty-ninth Street and Central Park; and thence across the Queensborough Bridge.