Here we have an 1840 Thomas Earnshaw London, silver pocket watch, no. 4501. It has a white enamel dial with Roman Numerals and a large sub-second dial. It has hallmarking from London assay office with the date letter ‘E’ which dates it to 1840. It has the case makers mark for Henry & Joseph Webb. It is a Fusee movement Duplex escapement which is keeping accurate time to within +10-15 seconds a day.
 
The white enamel dial is signed ‘Thomas Earnshaw, London, 4501’. It has a minutes chapter ring with the dot markers, 5 seconds dashes and 15 second diamond markers. There are large Roman Numeral hour markers, with the large sub-second dial at 6 O’clock. The sub-second dial has a clear railroad track with single second graduations and 10 second Arabic markers. It is original and a good tone. It has hairline fractures, but no chips or cracks.
The time is indicated with the spade and whip hour and minute hands in a gold tone. The sub-second hand is thermally blued and would appear to be original. 
 
The case is of open face design, with a hinged front and hinged case back. The pendant and loop and good and sturdy, with the silver hallmarking. There is a ribbed central design to the case. The rear has polished with age, with the rubbed circle to the centre. The case back opens to reveal the London assay office hallmarking. The inner case back is solid, with the hole for winding. The hinged front is opened to expose the dial. The push release at 6 O’clock hinges the dial and movement, to allow the movement to be seen. 
 
The movement is a Fusee with a Duplex escapement. It is signed ‘Thomas Earnshaw, No 119 High Holborn, London, 4501’. It has classic thermally blued screws with Diamond end stone. The level of finishing to the movement is lovely with a face engraved into the balance cock.
 
History:
Thomas Earnshaw was an English watchmaker who, following John Arnolds earlier work, further simplified the process of marine chronometer production, making them available to the general public. His other notable achievements include the invention of a spring detent chronometer escapement and a bimetallic compensation balance. 
 
The Spring Detent escapement was patented by Thomas Wright, who Earnshaw worked for, in 1783. With modifications by Earnshaw, it became the standard form in marine chronometers. 
 
In 1805 he was granted awards by the Board of Longitude for his improvements to chronometers. He received £2500 for his work. 
 
Setting these standards which became universal in marine chronometers are the reason Earnshaw is regarded as one of the pioneers of chronometer development.
 
Earnshaw passed at the ripe old age of 80 in 1829. Today, a blue plaque is situated on the premises of Thomas Earnshaw at 119 High Holborn, highlighting Earnshaw’s prestige as a watch and chronometer maker.
 
Please see the images as these compliment and aid the description provided below.
A further condition report is below.
 
Dial:
The dial is enamel and is in decent original condition. It has good and clear railroad track, with Roman numerals and signing. It is a bright white tone. There are no chips, but it does have hairline fractures. 
 
Hands:
The hands may be original. They are of Spade and Whip style with a gold tone. There is no bending to the hands. There is some marking to the surface. The sub-second hand is thermally blued and catches the eye.
 
Glass:
The crystal is a modern replacement, which is in good condition with only light marking.
 
Loop:
The pendent and loop are original and are in good condition, with visible hallmarking. The loop is nice and tight.
 
Case:
The case is silver and has a hinged front and rear, of open face configuration. It is in good condition for the age, with light surface scratching. It has the ribbed design to the centre which is still well defined. It is a good tone, with little tarnishing.
 
Front cover:
The hinged front cover is good, with light surface scratching and original finish. The hinge is good and sturdy.
 
Caseback:
The hinged case back is in good condition and closes tightly. It has a polished finish which is original and has polished with wear too. It has light surface scratching associated with age. The hinge is good. Inside it has clear British hallmarking from London Assay office. 
 
Inner case back:
The inner case back is solid, with the whole for winding. It has a polished finish with light surface scratching. Inside is the British hallmarking from London Assay office.
 
Movement:
The movement is a key wind Fusee with Duplex escapement. It has a gilt finish, with thermally blued screws and diamond end stone. 
 
The service history is unknown, but the movement is functioning well. It has a daily variation of +15 seconds a day. 
 
Case dimensions:
Case width: 51mm
Case length: 51mm
Case width with crown: 60mm
Case width with loop: 72.5mm
Case Depth: 20mm