Electric clocks
Electricity and magnetism
were phenomena known in the ancient world, but the first experiments into magnetic fields produced by electric currents did not take place until the early 19th century. Among the first to experiment with the use of electrically induced magnets to drive clock mechanisms was the Scotsman Alexander Bain 18 10-77), who patented an electric clock in the early 1840s. In the 19th century most electric clocks were used as precise master timekeepers, but from the early 20th century electric clocks for domestic use were also produced.
MASTER ELECTRIC CLOCKS
Bain’s first electric clock of the 1840s was powered by an earth battery which supplied an electric current alternately to two coils on either side of a magnetized bar on the pendulum bob. These regular electric impulses maintained the
swing of the pendulum. Sliding
contacts on the pendulum rod delivered the current alternately to coils in the movement, and the hands of the clock moved forward at each double swing of the pendulum. The movement was usually set in a simple wooden case, either wall-mounted or floor-standing. -Most surviving examples of Bain’s clock are museum-pieces. In Switzerland Matthaus Hipp (1813-93) developed the Hipp toggle c.1834, although it was not applied to clocks until 1842. This mechanism, featuring a toggle attached to the pendulum, gave an electric impulse only when the swing of the pendulum fell below a given arc. The inventions of Bain and Hipp facilitated the production of master timekeepers, which were much more accurate than purely mechanical clocks.
Further designs for electric master clocks followed in the early 20th century. In 1910 Percival A. Bentley of Leicester patented his “Earth Driven” clock, produced in a variety of case designs: his longcases typically had
well-made mahogany cases with bevelled glass trunk doors. One of the most precise electric master clocks, the “Shortt Free pendulum” clock, was developed by William Hamilton Shorts (1882-1971) and Frank Hope-Jones (1867-1950) between 1921 and 1924. This clock was extremely accurate – losing or

gaining only one or two-thousandths of a second every day – and was used as a standard timepiece for observatories until the development of the caesium atomic clock in the 1950s.
DOMESTIC ELECTRIC CLOCKS
Probably the most successful early domestic electric clock was that manufactured between 1909 and 1914 by the Eureka Clock Co. in Clerkenwell, London. Patented in 1906, it used the same principle as Bain’s electric clock, but instead of the pendulum the balance wheel was impulsed. Eureka clocks were very well made with a variety of case designs: the most desirable are those in which the movement is visible. This type, like the skeleton clock, was covered by a glass dome.
One of the most common electric clocks found today is the Bulle clock, invented by Monsieur Favre-Bulle. This clock was patented in 1922 in Britain, but most examples were manufactured in France; production ceased at the beginning of World War 11. The earliest Bulle clocks have circular mahogany bases, with the battery housed in a vertical brass pillar and the movement covered by a glass dome; in later examples the battery is housed in the base. In the 1930s some electric shelf clocks with plastic cases operating from mains electricity were produced: these arc becoming increasingly collectable with the growing popularity of 1930s Art Deco pieces and the interest in such early plastics as Bakelite.

• CARE glass domes supplied with skeletonized Eureka and Bulle clocks may be missing and are difficult to replace; reversing the battery connections of a nonworking Bulle clock may be sufficient to restart it; if a Bulle clock requires a battery, this should be no more powerful than 1 1/2 volts
• COLLECTING 19th-century electric master clocks are rare; the most collectable Eureka clocks are those with a visible oscillating balance wheel; visible movements are generally more desirable than concealed ones

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