clock mechanism was refurbished in 2000; it is complete and intact, despite two previous modifications. The Ferry Building has its original Special #4 clock made in 1898 by the Boston clock maker E. Howard. It was the largest wind-up, mechanical dial clock in the world but is now powered by an electric motor. The four dials are each in diameter, and a portion of the dial appears to be back-lit at night. This is the effect of two concentric dials on each clock face, in which the inner dial is lit and visible at night. Although the hands and a small portion of the works are now powered by an electric motor, the entire clock mechanism is still there. The huge weight hangs in its shaft; once wound, it formerly kept the clock running for eight days. The pendulum also remains, but it is motionless, replaced by electric power. There is also a set of horn loudspeakers above the clock that play Westminster Chimes on the hour and make a loud siren noise every Tuesday at noon on the hour. Ferry service The Ferry Building is the primary San Francisco terminal for commuter ferry service (Pier 41 is used primarily for excursions). The facility has six ferry piers lettered Gate B through Gate G. Gate B, used by the San Francisco Bay Ferry Vallejo/Mare Island route and the Treasure Island Ferry is adjacent to the north end of the building. Gates C and D are the Golden Gate Ferry Terminal, located on a larger wharf near the center of the Ferry Building. They are used by Golden Gate Ferry service on the Sausalito, Tiburon, and Larkspur routes. Gates E through G are located south of the south end of the building; they are used by San Francisco Bay Ferry services on the Oakland/Alameda, Alameda Harbor Bay, and Richmond routes. Privately run service to Berkeley docks at Pier 1 to the north. The Golden Gate Ferry Terminal, which is located on a wharf built in the late 1960s as part of the Transbay Tube, opened with the introduction of Golden Gate Ferry in 1976. Vallejo service was added in September 1986. When emergency ferry service was added after the 1989 earthquake, Alameda service docked between Pier 7 and Pier 9, Berkeley service docked at Pier 1, and all other service used the existing Ferry Building piers. Berkeley and Richmond service ended