Marine chronometer by Henri Motel

Description — British Museum

Marine chronometer; pivoted detent escapement; movement in brass canister gimballed in mahogany box; tipsy key; flat engraved silvered brass dial with recessed subsidiary seconds; blued steel hands; contains purchase note from Messrs Beguet.

Curator's comments — British Museum

Comment from Anthony G. Randall and Richard Good, Catalogue of Watches in the British Museum. Vol. VI (1990) Made by Henri Motel, c. 1826 Marine Chronometer Signature: On the dial MOTEL N° 44. On the edge of the dial ring HRI MOTEL HGER DE LA MARINE RLE. Box: The movement fitting with a bayonet and catch, in a heavy brass canister,… the bottom glazed, the dial protected by a glazed bezel fitting on the outside of the canister where it is held by three screws. On the wide flange of the bezel at III o'clock there is a sliding shutter over the winding hole. The canister fits in a brass cradle lined with green velvet, gimballed in a well-made dark mahogany box. A brass knob in the bottom right-hand corner of the box operates on a bar pivoted on the bottom of the box. This acts on the bottom of the hemispherical brass weight on the underside of the cradle and locks the gimbal assembly. A small well-made tipsy key numbered 161 fits in the other right-hand corner. There is the usual lock for the box, a sliding panel with diamond-shaped brass piece inset engraved N 44M with brass ring to retain the glass (now missing) over a circular aperture in the lid and an ivory disc set in the front of the top of the box. This last is engraved 44 MOTEL * L. LECOCQ, it has an integral threaded portion passing through the wood panel and held by an ivory nut at the back. There are no carrying handles. Base 165 mm square; sides 160 mm square; h. 137 mm square. A label inside the lid reads: L. LEROY & Cie HOROLOGER DE LA MARINE 7, BOULEVARD de la Madelaine PARIS. Date des Huiles 44 Juiee 1917 Dial and hands: Flat engraved, silvered brass dial with recessed subsidiary seconds, the engraving filled with black wax, the surface of the dial frosted. Two round dial feet, soft soldered on, pass through holes in the front plate and have screws passing into tapped holes. Blued steel hands. Movement: Dial ring diam. 80.4 mm; front plate diam. 75.1 mm; back plate diam. 73.8 mm; frame h. 18.2 mm. Frame: Full plate construction with four finely grained steel pillars attached to the front plate by brass nuts and to the back plate by polished steel nuts and blued steel washers. The dial ring is recessed for both the front plate and the dial, and is held by two shouldered screws on the front plate under the dial. The escapement is mounted on a separate plate on four short steel pillars attached to the inside of the front plate. The bridge over the balance also has four steel pillars, two hollow for the fixing screws. The layout and construction is similar to that of Louis Berthoud's, including the case catch. There are holes in the back plate to view the great wheel-centre pinion and centre wheel-third pinion gearing. Fusee: Fitted with the English type of stop-work, the return spring for the stop piece is fitted on the outside of the back plate and acts through a hole in the plate. The Harrison maintaining power has a steel ratchet wheel. The setting-up-work is on the dial side of the front plate. The barrel has a wide flange on the cover end, the arbor is solid and unsnarled, the main¬spring is hooked with an eye at both ends and there is a bride which is signed 'Vincent Juillet 1826'. The great wheel assembly is held on the fusee by a plate and two screws passing into the central boss of the fusee iron. The steel ratchet wheel is cut on the edge of the fusee iron. Going train: Very well made and finished, the pinions and arbors black polished, the centre wheel held with two screws passing into the pinion, the fourth wheel similarly held to a brass collet. The wheels decorated with patterns of stripes. Jewelling: The third arbor pivot and those of the fourth, escape pinion and balance staff in pierced jewels. With the exception of the fourth front bearing, endstones are provided for all the jewelled bearings including a diamond on the balance bridge. Where possible steel end plates are fitted to all the going-train bearings, the bearings themselves being detachable brass bushes. Escapement: Pivoted detent escapement showing a close resemblance to those of Louis Berthoud. The brass escape wheel is recessed on both sides leaving only the tips of the teeth the full height. Each tooth is pierced with a small hole just below the tip, and the wheel is mounted on a steel collet on the arbor. The locking stone jewel is of rectangular section where it is set in the detent, and has one long and one short side rounded on the acting portion. The tail of the detent banks against a disc of jewel mounted in a brass bracket. The various cocks on the detachable escapement platform have steel steady pins. The impulse roller is set with a radial jewel, and the edge is snailed, it is held by two screws on an integral collet on the staff. Balance: Bimetallic four-armed balance with cylindrical brass compensation weights. The steel parts of the balance are blued, and it is fixed with two screws to a brass collet on the staff. Steel timing screws are set in the rim at the ends of the arms. Diam. 27.3 mm, h. 2.1 mm. Balance spring: Blued steel conical spring of 13½ turns without terminal curves. The smaller end clamped concentrically to the stud, the larger end similarly clamped to the stud. This has three levelling screws. Going-train counts: Great wheel (fusee) 104 teeth, 8 turns of groove Centre pinion 26 leaves, wheel 128 teeth, 4 arms Third pinion 16 leaves, wheel 120 teeth, 4 arms Fourth pinion 16 leaves, wheel 140 teeth, 4 arms Escape pinion 14 leaves, wheel 15 teeth, 4 arms Beats per hour: 18,000. Motion work: Cannon pinion 18 leaves, minute pinion 16 leaves Hour wheel 64 teeth, minute wheel 54 teeth The minute wheel and pinion are pivoted between a cock and the front plate. The hour wheel runs on a steel pipe set in a bridge over the cannon pinion. Winding work: A brass wheel of 50 bevel teeth is carried on a steel shaft pivoted in brackets on the inside of the movement canister. It has a squared end for winding. The wheel is in permanent m