3. Landeron 4750/51

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F.3 Landeron 4750/51

Ebauches S.A. (ESA) was the company that brought Switzerland its first fame in the production of electric wrist watches, when, after approximately ten years of research by André Beyner and René Besson, the Landeron '4750/51' was produced. Since most parts were manufactured at ESA's branch in Landeron, the watches were named the 'L 4750' and 'L 4751', the 'L' indicating the watches had been produced at Landeron. Swiss patents were granted under nos. 345611 and 346828 (1959). The movements were assembled by a few selected firms, amongst which Leonidas, at that time a well known chronograph factory. The batteries were the Mallory WD-4 or the rechargeable 15P 3.5, manufactured by Leclanché.

1959	April 20th, application for patent no. 346828 CH is filed.
1960	At the end of 1960, the 'L 4750' movements come into production.
1961	April 15th, the first complete watches with the L 4570 are shown at the Basle Fair.
1961	The second version, the 'L 4751' comes into production. The start of sales of the much thinner and cheaper Lip R 148 signalled the halt in the production of the 'L 4751' already six months after the latter was first introduced. At this time, about thirty watch manufacturers sell watches with this movement amongst which: Favre Leuba, Benrus, Borel, Camy, Rotary, Royce, Eska, Avia, Admiration, Admes, Schild, Onsa, Huguenin, Gruen and Pontiac (Pontilectric). Two different models of the L 4750 were produced. One with a small dry cell, the other with an accumulator built in the back of the case, which needed recharging every six months by use of a simple flashlight battery of 1.5 Volts. To do this one had to pull off one of the two crowns and connect the flashlight battery to the watch case. A special shaped instrument, to connect the watch with the battery, was sold together with the watch. The 'L 4751' was a slightly modefied version of the above and only produced in the dry cell version. Improvement of the watch led to an increase in the battery's life span, a decrease of problems with magnetic fields and the addition of a stopping device, which stopped the balance so that the time could be accurately set. A demonstration model, the 'Montre ê Couilles', was also manufactured, containing two batteries of which one is a reserve battery. The back of the watch is transparent.

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