On offer today we have something quite special, dating from 1947, we have a beautiful stainless steel case, Art Deco, California dialled Eterna bumper automatic gentlemans watch. The dial really makes the watch and examination under the binocular microscope reveals that although the indices and hands have been relumed, the dial is orginal and un-refinished. Case diameter is approx. 36mm. The case back carries the folowing inscription in gothic script, "Alistair MAckenzie 22nd December 1947: From Mum & Dad." The watch presents on a Foxstraps Argentinian manufactured, grey, croc grain leather strap.
Removing the caseback and taking a look inside revealed an Eterna Cal. 1076H: -
Features; automatic (bumper); sub second.
Data; 13''', Dm=Do= 29.4mm, H= 5.4mm, 19/21 jewels; f = 18000 A/h, power reserve 36h.
Parts: Balance staff U1697, Stem W2057, Main spring 1.60 x 8.5 x 0.08mm, Hands 1.30 x 0.70 / 0.22mm.
Bumper automatics were the first self-winding wristwatches, and were initially developed and patented by John Harwood in 1923, a watch repairer from Bolton. Harwood’s system uses a pivoting weight which swings back and forth as the wearer moves, transferring power to the mainspring. The motion of the winding rotor is restricted to an arc of around 300 degress, at which point the rotor bumps against one of two stops, each protected by a spring. This abrupt halt can be felt when wearing (or holding) the watch, hence the name ‘bumper automatic’. Another feature of bumper automatics is that they only wind the mainspring in one rotor direction. In the return direction, the mechanism simply ‘freewheels’ back to the starting position.
This beautiful watch has been fully serviced by a master watchmaker and is keeping time beautifully.