Most longcase clocks are cable-driven, meaning that the weights are suspended by cables. If the cable were attached directly to the weight, the load would cause rotation and untwist the cable strands, so the cable wraps around a pulley mounted to the top of each weight. The mechanical advantage of this arrangement also doubles the running time allowed by a given weight drop. Cable clocks are wound by inserting a special crank (called a "key") into holes in the clock's face and turning it. Others, however, are chain-driven, meaning that the weights are suspended by chains that wrap around gears in the clock's mechanism, with the other end of the chain hanging down next to the weight. To wind a chain-driven longcase clock, one pulls on the end of each chain, lifting the weights until the weights come up to just under the clock's face. Elaborate striking sequences In the early 20th century, quarter-hour chime sequences were added to longcase clocks. At the top of each hour, the full chime sequence sounds, immediately followed by the hour strike. At 15 minutes after each hour, 1/4 of the chime sequence plays, at the bottom of each hour, 1/2 of the chime sequence plays, and at 15 minutes before each hour, 3/4 of the chime sequence plays. The chime tune used in almost all longcase clocks is Westminster Quarters. Many also offer the option of Whittington chimes or St. Michael's chimes, selectable by a switch mounted on the right side of the dial, which also allows one to silence the chimes if desired. As a result of adding chime sequences, all modern mechanical longcase clocks have three weights instead of just two. The left weight provides power for the hour strike, the middle weight provides power for the clock's pendulum and general timekeeping functions, while the right weight provides power for the quarter-hour chime sequences. Types Comtoise Comtoise clocks, also known as Morbier clocks or Morez clocks, are a style of longcase clock made in the French region Franche-Comté (hence their name). Features distinguishing this style are a curving "potbellied" case and a greater use of curved lines. Often a heavy, elongated, highly ornamented pendulum bob extends up the case (see photo). Production of these clocks began in 1680 and continued for a period of about 230 years. During the peak production years (1850–1890) over 60,000 clocks were made each year. These