Weight Driven and Pendulum Clocks

There are two basic types of mechanical clocks, those powered by weights and those powered by springs. Weight-driven clocks came first, used in churches and monasteries beginning in the 13th century. The heaviness of a clock’s weights powers its movement (the network of gears and pins that move the hands of the clock), which is regulated by the escapement. In the 1650s, pendulums were added to clocks to make them more accurate. Inventor Christiaan Huygens developed the first pendulum clock in 1656 and patented the design the following year. Clocks driven by swinging weights reduced timekeeping inaccuracies from around 15 minutes per day down to 15 seconds per day, thus flourished up until the early 20th century. Weights were used on all manner of clocks, from tall grandfather clocks to highly accurate regulators to hanging wall clocks, which include decorative cuckoo clocks. In the United States, one of the earliest weight-driven clocks was made in the late 18th century by Simon and Aaron Willard, whose Massachusetts Shelf Clock, as it was known, was basically a smaller version of a tall-case clock, with a brass dial and a mahogany pedestal base. In 1802, Simon Willard would cement his name in horology history when he created the banjo clock. Even more influential was Eli Terry’s 1816 pillar-and-scroll weight-driven shelf clock, which took its name from the vertical, finial-capped pillars on the sides of the clock, as well as the decorative scrolls at the top. Introduced in the early 19th century, Terry’s earliest model exposed the escapement and pendulum on the front of the dial; subsequent models hid these mechanical features inside with the rest of the clock’s wooden movement. Numerous Connecticut clockmakers, including Seth Thomas, quickly copied Terry’s basic design. Thomas’s wooden-movement shelf and mantel clocks first appeared in 1817. These, too, had pillar-and-scroll cases, usually with a bucolic scene painted on the bottom third of the case below the clock’s face. Later in the century, another Connecticut clockmaker, Ansonia, manufactured an extensive line of weight-driven mantel clocks with elaborately painted china cases, along with weight-driven regulators like the General. By the middle of the 19th century, springs had largely replaced weights as the primary means to power a clock. Movements were also upgraded. Once made of wood, the wheels and pinions were now made of tougher brass, which made their leaves, or teeth, less susceptible to chipping or breaking outright. Weight-driven regulator clocks remained the standard for accurate timekeeping until the invention of quartz movements by Warren Marrison and J. W. Horton at Bell Telephone Laboratories in 1927.