Rare 18s 19J Waltham 1892 Astronomical SIDEREAL dial c1910
Only 325 of these pocket watches were produced by Waltham. They all have an 18s 19J 1892 grade movement with a true 24 hour dial which measures sidereal time as opposed to solar time. The watch measures sidereal time and thus works -4 minutes a day.
Sidereal time, time as measured by the apparent motion about the Earth of the distant, so-called fixed, stars, as distinguished from solar time, which corresponds to the apparent motion of the Sun.
A solar day is the time it takes for the Earth to rotate about its axis so that the Sun appears in the same position in the sky. The sidereal day is ~4 minutes shorter than the solar day. The sidereal day is the time it takes for the Earth to complete one rotation about its axis with respect to the 'fixed' stars.
Movement – the nickel full plate 1892 movement has a lever escapement and is decorated with damascening. The high quality movement has a micrometer regulator with a diamond endstone, gold train wheels and large gold jewel settings. The movement is signed “A.W.W.Co, Waltham Mass, 19 Jewels, Adjusted 5 positions” # 18028559. The movement also has an unusual configuration on the motion work under the dial to operate a true 24 hour dial. The movement is in 95% mint condition
Case – the movement comes in a white metal open face case, which has a screw off bezel and the movement swings out of the case. The case has a smooth plain finish and is engraved “TS.2292” on the back. The case is in 90% mint condition – a build up of light marks and scratches over the years creating a matt finish
Dial – the white enamel dial has a true 24 hour dial with a full set of blue steel hands. The dial is signed “Waltham, Sidereal” and is in 90% mint condition – a small hairline on the 6-7.
The watch has a bevelled mineral glass
The watch is stem wound / lever set
The watch measures 58mm wide x 20mm deep
Early 20th Century
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