- Museum number
- 1972,0903.5
- Description
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Chronometer watch.
Spring detent escapement; fixed winder on fusee square; set hands on centre.
White enamel dial; up and down dial below XII; subsidiary seconds above VI; blued-steel hands.
Open face 18ct gold case with inner dome.
- Production date
- 1869 (case)
- Dimensions
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Diameter: 54.30 millimetres (case)
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Thickness: 13.50 millimetres (case)
- $Inscriptions
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- Curator's comments
- Comment from Anthony G. Randall and Richard Good, Catalogue of Watches in the British Museum. Vol. VI (1990)
Made by Charles Frodsham, 1869
Chronometer
Signature: On the back plate 'Chas. Fordsham 84 Strand LONDON 01380 AD Fmsz', the last being obscured by the ring around the winding key. Also signed on the dial, just above the centre 'CHAs FRODSHAM OI380 AD F.msz'.(1)
Case: Open face 18-carat gold case with the London hallmark for 1869 and the casemaker's mark J.W in an oval. The cuvette and engine-turned back hinged to the middle, the later decorated with a reeded pattern. The pendant solid, and with the maker's mark TC. NO push-piece or case springs. The cuvette marked with an arrow to show the direction of winding. The case back centre has been thinned down to remove a crest or monogram. Diam. 54.3 mm, overall h. 13.5 mm.
Dial and hands: Flat enamel- dial with sunk subsidiary seconds and sunk centre of the up-and-down dial, fixed to the front plate by three feet and pins. The copper edge of the dial and the three feet have been gilded.
The minute and hour hands of gold and of spade design, the up-and-down and seconds hands of blued steel.
Movement:
Ebauche marks 18, 2, 691, 01380.
Front plate diam. 46.1 mm; back plate diam. 43.2 mm; frame h. 7.4 mm.
Frame: Typical half plate construction with three turned pillars, the back plate retained by recessed blued steel screws. There is no separate bridge on the front plate under the dial, and there are a number of unfilled milled recesses and holes, possibly for fusee keyless work never fitted. The movement is held in its case by a peg and a single dog screw opposite, in the edge of the front plate.
Fusee: The fusee wound by a blued steel folding key fitted on the arbor square, the usual stop-work and maintaining power, with a steel maintaining ratchet wheel. The setting-up-work with a fine toothed blued steel ratchet wheel and two polished clicks with polished return springs fitted on the back plate. The barrel arbor with an extended square on that end only. The barrel with a small flange on the cover end. A small pinion on the lower end of the fusee meshes with a wheel carrying the up-and-down indicator hand.
Going train: The usual layout and design, the centre pinion hollow for the hand-set arbor carrying the cannon pinion and having a setting piece with grooves for the finger nail. The brass wheels gilded, the steel pinions and arbors well finished and polished.
Jewelling: The upper pivot of the fusee arbor, and those of the going train and escapement arbors, in pierced jewels, those of the escapement and most unusually the fourth upper pivot with endstones. A diamond endstone set in a blued steel ring on the balance cock. All the jewels are well made and finished, the train jewels are bombé.
Escapement: A development of Earnshaw's spring detent escapement. The brass escape wheel with arms and rim sunk below the level of the teeth, and with a dog screw to lock the wheel. The impulse roller made from a solid piece of clear sapphire, and with the impulse face leaning slightly towards a radial to the tip. The polished steel discharge roller with a small flat for adjusting, and jewelled in the usual way. The detent with polished sides, edges and top having a small half-round locking stone, and a gold passing spring held with a screw, planted with the centre line of the foot well inside a tangent to the locked tooth. Banking for the detent, against the locking stone pipe, provided by a small gold screw set in an arm projecting from a polished steel semicircular foot concentric with the balance staff.
Balance: Bimetallic two-armed balance with gold screws, and nuts at the ends of the arms. The other two quarter nuts of platinum. Diam. of rim 16.5 mm, h. 1.91 mm.
Balance spring: Blued steel duo-in-uno balance spring free sprung and with upper terminal curve to a diamond-shaped polished steel stud on the balance cock, and to a polished steel collet on the balance staff (see cat. no. in for a similar example).
Going-train counts:
Great wheel (fusee) 72 teeth, round bottom tooth form
Centre pinion 12 leaves, wheel 80 teeth, 6 arms
Third pinion 10 leaves, wheel 75 teeth, 6 arms
Fourth pinion 10 leaves, wheel 80 teeth, 6 arms
Escape pinion 8 leaves, wheel 15 teeth, 3 arms
Beats per hour: 18,000
Motion work:
Cannon pinion 12 leaves, minute pinion 10 leaves
Hour wheel 40 teeth, minutes wheel 36 teeth
Up and down pinion 10 leaves, wheel 60 teeth, 5 arms, not gilded
Provenance: Bequeathed by Mr F. R. S. Rogers in 1972.
Note:
(1) This is British work at its best. It is thought that 'AD Fmsz.' represents 1850, the year in which Frodsham began making high-quality watches.
Bibliography: Mercer 1981.
- Location
- Not on display
- Condition
- Latest: 2 (2017)
- Acquisition date
- 1972
- Department
- Britain, Europe and Prehistory
- Registration number
- 1972,0903.5
