Vintage and Antique 400-Day Clocks

The torsion clock, typically known as a 400-day clock in the U.K and the anniversary clock in the United States, was first developed by Aaron D. Crane in 1841 using a rotary—rather than swinging—pendulum invented by Robert Leslie nearly 50 years earlier. Crane’s clock, which was designed to run for more than a year without winding, was driven by an escapement activated by this style of spinning pendulum, which Crane hung from a slender wire. Despite its early 19th-century roots, the torsion clock wouldn’t gain popularity until the 1880s, after a German inventor named Anton Harder independently designed and patented a clock with a torsion pendulum inspired by a rotating chandelier. In 1881, August Schatz founded the Wintermantel Company, which manufactured designs based on Harder’s patent and was eventually renamed Jahresuhrenfabrik or “Year Clock Factory.” After the patent lapsed in 1887, several clockmakers in Germany’s Black Forest region began manufacturing torsion clocks that only needed winding once a year. These companies included Gustav Becker, Kieninger & Obergfell (also known as Kundo), Lenzkirch, Kienzle, and Junghans. Suddenly, clocks with long running times were being produced en masse. The long-running capabilities of 400-day clocks relied on the slow turns of a torsion pendulum—often as few as eight per minute—as well as intermediate pinions and wheels between the mainspring barrel and the rest of the movement. Most antique 400-day clocks were constructed with a heavy spherical ball or cylinder-shaped pendulum hanging beneath the movement that would rotate slowly in one direction and then the other. Beginning around 1900, these pendulums were generally made from an assembly of three or four brass balls. The entire clock was often positioned under a glass dome, allowing the interior mechanism to be clearly visible, which is sometimes known as a skeleton movement. By the early 20th century, 400-day clocks were popular wedding gifts as their once-a-year winding requirement made them perfect for such a sentimental anniversary tradition. In 1954, the Schatz company developed a new model that would run for 1,000 days. However, the most desirable antique torsion clocks are generally the 400-day models made before 1914 by either Jahresuhrenfabrik or Gustav Becker.