Stainless steel cased world-time centre-seconds day-date tuning-fork wrist-watch with black lizard-skin strap

Description — British Museum

Battery powered mechanism with tuning-fork timing device/escapement. Dial with outer rotating white painted ring inscribed with locations around the world; luminous-painted baton hour marks; date aperture at 3 o'clock. White-painted hour and minute hands with luminous-painted bars; red-painted centre-seconds hand. Stainless-steel case with screw-on back. Lizard skin wrist-strap with chromium-plated buckle. When acquired contained a battery.

Curator's comments — British Museum

Text from 'Watches', by David Thompson, London, 2008, p. 156-157. Bulova Watch Company STAINLESS-STEEL, WORLD TIME 'ACCUTRON' WRISTWATCH NEW YORK, c. 1970 SIGNED: 'BULOVA PATENTED STAINLESS STEEL 666 FEET' (on the case back); ACCUTRON DEEP SEA 666 FEET' (on the dial) On 19 June 1953 the Bulova Watch Company of New York registered in Switzerland patent no. 312290 for a timekeeping device based on the oscillation of the free ends of a tuning fork. The concept had been realized by the Swiss-born engineer Max Hetzel, who at the time was working for Bulova in Bienne, Switzerland. As well as the tuning fork, an essential component of Hetzel's new timekeeping device was the newly invented transistor. In 1954 the world's first tuning-fork timekeeper - an electronic clock - was exhibited in Paris. The main obstacle to the production of a device small enough to be used in a watch was the lack of a long-life battery; this was overcome just a year later by the production of a new form of miniature zinc-mercuric oxide alkaline battery developed by Philip Rogers Mallory and Samuel Ruben at the Mallory Battery Company. The following year prototype watches were produced in Bienne. While confidence in the viability of the watch was limited in Switzerland, in America its potential was viewed differently. Max Hetzel and William Bennett perfected the design in New York, and in 1960 Bulova launched the 'Accutron' watch in that city as a viable production-model wristwatch. The Bulova calibre 214 was announced as the first fully electronic watch in the world. The tuning-fork mechanism works on the principle of using transistorized electronics to switch on and off small electromagnets, which keep the tuning fork arms vibrating at a frequency determined by their length, mass and elasticity. In the Accutron, this frequency is 360 oscillations per second. The vibration of the tuning fork is then transformed into circular motion using an extremely fine-toothed ratchet wheel and two tiny ratchet pawls. One pawl, moved by the tuning fork, pushes the wheel round in one direction, and the other, fixed to the watch plate, prevents the wheel from reversing. Production of this wheel was as much of a challenge as the electronic circuitry required for controlling and switching the electromagnets. The index wheel in the Accutron is less than five hundredths of a millimetre thick and has three hundred teeth, each just one hundredth of a millimetre high. The movement version contained in this watch, as seen from the inscription 'U.S.A. BULOVA 2182' on the case back, is the 2182 model, first made in 1968. The watch has a world-time dial with a manually adjusted outer white painted ring inscribed with locations around the world. To use this function, the normal fixed chapter ring with twelve baton markers has to be seen as a 24-hour ring; this, however, is not made easy because there are no half-hour divisions. Indeed in some models of this watch the dial is numbered with odd numbers from 1 to 23 between the baton hour marks. In order to use the watch in this way, the ring must be rotated using the button in the case band at 4 o'clock, so that the present location of the watch is indicated against the appropriate 24-hour mark on the fixed dial. For example, if it is 3 p.m. at Greenwich, the red Greenwich triangle is set to the 15 position - i.e. 7.30 - on the fixed chapter ring. The time at the other locations shown around the dial can then be read (taking into account, of course, any variations such as British Summer Time). The second button in the case band is for hand-setting in the normal way. The calibrations on the dial are luminous and there is a rectangular date aperture on the right. For divers, the inscription on the dial claims a resistance to water intrusion to a depth of 666 feet, and the sturdy stainless-steel case is complemented by a black lizard-skin wrist-strap with the name 'Accutron' on the inside.