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D Early Prototypes

In professional literature some prototypes are mentioned, which never reached the industrial production phase:

Prototype pocket watches

D.1The 'Goud, Zilver and Klokken Museum' in Schoonhoven, The Netherlands, is in possession of two very interesting electric pocket watches most likely manufactured by Diederik A. Sardemann or Cornelis D.J. Jamin before 1910. They are probably the first known completely new designed electric watches that have not been converted mechanical pocket watches.
D.2The collection of Mr. Barny in New York City, contains a converted pocket watch. This watch is powered by a battery that is added to the outside of the case. The watch was manufactured around 1925. An electromagnet winds the main spring once per hour.
D.3The 'Bulletin d'Information Hugo Buchser', issue of February 1954, tells the story of a Finnish soldier and watch maker who created an electric watch in his spare time in 1944. Unfortunately no further information is available about this particular watch.

Prototype wrist watches

D.10André Beyner describes in the 'Journal Suisse d'Horlogerie', issue of October 1955, an electric wrist watch with mechanical contacts and a micromotor. The first time this watch ever worked was recorded as December 1953.
D.11The French firm Leon Hatot, producer of the famous ATO clocks, presented a wrist watch with transistor, micromotor and a Mallory mercury cell at the Congress of the French Chronometric Society, held November 24, 1956. The watch was constructed by Marius Lavet and Mr. Dietsch.
D.12A letter written by Dr.A.L. Rawlings, published in the American magazine 'National Jeweler' in May 1956 explains his attempts at making an electric watch. It was made as a personal challenge which started from reading a report on the joint venture between Elgin and Lip. He started with a small standard watch movement, threw away the mainspring and barrel which gave him room for a battery and applied a magnet to wind up the new mainspring (consisting only of a small helix of wire hooked on to the third wheel) every 15 seconds. The contact, therefore, closed only four times a minute instead of 120 times. The magnet and the contact maker were the only important parts that had to be specially designed and made. With the skilful help of a good model maker the first model was made from this drawing, cased and set going in March 1954, followed by a second slimmer watch.
D.13The 'Longines Conquest Electric' caliber 400 was to become the first electromechanical wrist watch in Switzerland. Longines showed it for the first time in 1961 at the Basle Fair. There are many publications about this watch. See: 'Bulletin de Société Suisse deChronométrie' pg. 693-695, 1962. It just missed commercial production. This watch's system is equal to the old galvanometer with a moving coil. Every time the small pin on the balance pushes two mechanical contacts together, the coil is energised, turns 90 degrees, pushes a wheel one tooth forward and is moved back by the balance wheel. This watch should not be confused with the Longines Conquest Electronic with a Dynotron transistorised movement.

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Copyright © by Pieter Doensen

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