Regulator clock

A precision pendulum clock kept as the standard for checking other timekeepers, and later a name stenciled on American wall clocks of every grade.

What a regulator clock is

In the strict sense, a regulator is a precision pendulum clock that serves as a standard. The Smithsonian's National Museum of American History describes regulators as precision clocks used to time scientific observations and to regulate other clocks and watches. Observatories, jewelers, railroads and telegraph companies all relied on them.

The word has two other uses. The Vienna regulator is a family of fine wall clocks named for that precision heritage, and in the United States Regulator became a model name painted on wall clocks that ranged from true precision instruments to ordinary spring-driven timepieces.

How a precision regulator keeps time

A regulator strips the clock down to the job of keeping time. The Seth Thomas Regulator No. 2, for example, uses a falling weight for steady power, a Graham deadbeat escapement that avoids the backward recoil of older designs, and maintaining power, which keeps the clock running while it is being wound.

Temperature is the next enemy, because a pendulum rod grows longer as it warms and the clock slows. George Graham's answer was the mercury pendulum, which replaces the solid bob with a jar of mercury. As the rod lengthens, the mercury expands upward, keeping the pendulum's effective length steady. The Banco de España's collection notes date his first one to 1721, and the British Museum notes that he described it to the Royal Society in a paper of 1726.

Many regulators also use a distinctive dial. A wall regulator of about 1880 by Asmus Johannsen of London, in the Banco de España collection, shows minutes on its largest dial, seconds on a small dial above and hours on a small dial below, so the minutes and seconds can be read at a glance. The clock stands 178 centimeters tall and displays its mercury pendulum behind a glass front.

See also: the escapement, pendulum and weights in a typical movement on OnlineClock.app.

Observatory and shop regulators

Astronomers needed accurate time to fix the positions of stars, and in 1676 the London maker Thomas Tompion built two specially designed regulators for the new Royal Observatory at Greenwich. One, now in the British Museum, has a 13-foot pendulum that takes two seconds per swing, a deadbeat escapement designed by Richard Towneley and enough power to run a full year on one winding. The first Astronomer Royal, John Flamsteed, found the clocks accurate to within eight seconds a month once their escapements had been adjusted.

Regulators also served commerce. The Smithsonian holds an 1874 regulator by E. Howard and Company of Boston, about 79 inches tall in a mahogany and burl walnut case, made for the Gold and Stock Telegraph Company. Contacts on its movement broke a telegraph circuit every half minute, minute, five minutes and hour, sending Philadelphia time to subscribers who could set their own clocks by it.

Jewelers kept regulators so they could set the watches they sold and repaired. The Henry Ford displays a mahogany wall regulator about 69 inches tall in the Grimm Jewelry Store at Greenfield Village. The building once stood on Michigan Avenue in Detroit, where Engelbert Grimm sold and repaired watches, clocks and jewelry from 1886 to 1931. The museum dates the clock to between 1850 and 1910 and credits it to the Waterbury Clock Company, with a movement made in France or Switzerland.

The Vienna regulator

The best-known clocks to carry the name are Vienna regulators: tall, narrow, glazed wall clocks with weight-driven pendulum movements that developed in Vienna around the end of the eighteenth century. Fine examples used deadbeat escapements and were genuinely accurate, but after about 1850 German factories turned the look into a popular household clock made in far greater numbers.

Their styles, makers and the clues that separate a Viennese clock from a German one are covered in our full article on the Vienna regulator.

Regulator as an American model name

American companies sold many wall clocks with Regulator in the model name. The Seth Thomas Regulator No. 2 is one of the best known. According to the collector reference Antique Clock Guy, it was introduced in the early to mid-1860s and made until 1950, with a 12-inch dial, a case about 34 to 36.5 inches long and four different movements over its life. It was trusted enough that railroads hung it in stations to give travelers the correct time, and Seth Thomas reissued it in 1976 in a run of 4,000.

Other clocks borrowed the word more freely. The restorer behind the antiquevintageclock.com blog points out that a Gilbert calendar clock advertised as a Regulator had only a spring-driven, time-only movement, which he says is accurate to within a minute or two a week, not close enough to set other clocks by. By contrast, a double-weight Welch, Spring and Company clock made from about 1874 to the mid-1880s was certified for train stations, and buyers could tick a box on the order form to have Regulator stenciled on its door.

Antique Clock Guy notes that No. 2 cases began in walnut veneer, added cherry and oak around 1890 and ended in mahogany and oak around 1913, and that some later cases carry a stamped or stenciled month and year on the back.

How to recognize a true regulator

Do not rely on the word itself. A clock with Regulator painted on its glass may be a precision timekeeper or simply a well-marketed wall clock, so look at the mechanism instead.

Signs of real precision include weight drive, a deadbeat escapement, maintaining power and a seconds hand, either in a subsidiary dial or as a separate regulator-style dial. A temperature-compensated pendulum, such as a mercury jar, is another strong clue, and the Howard regulator even has a silvered beat scale for checking that the pendulum swings evenly. A spring-driven, time-only movement behind a Regulator label tells you the name was chosen for sales rather than service.

See also: the atomic standards that took over the regulator's job on OnlineClock.app.

Keep exploring

Sources

1. Observatory regulator by Thomas Tompion, British Museum (Google Arts and Culture)
2. Howard Regulator, 1874, National Museum of American History (Smithsonian)
3. Regulator wall clock by Asmus Johannsen, Banco de España Collection
4. Wall Regulator Clock, Used in the Grimm Jewelry Store, 1850-1910, The Henry Ford
5. Seth Thomas Regulator No. 2 History, Antique Clock Guy
6. If it says Regulator on your clock it is likely NOT a Regulator?, antiquevintageclock.com

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