6 feet 2 inches (1880 mm)
The very substantial flat top solid mahogany case with bombe-shaped trunk and conventional base. The hood with concave main top moulding above the canted and fluted hood sides, the sides with blind aperture mouldings, and the whole hood extended top and sides to seal with the massive 2 inch thick backboard, also extended to match the hood, which is sealed with longer hood sealing screws, each knurled and number stamped 2, to correspond with the inlaid brass numbered hood holes. The hinged and glazed hood door, similarly screw sealed, the glass with a sealed gilt-brass winding shutter or ‘valve’. The trunk with concave throat moulding, and further conforming sealing screws up into the hood, above the trunk with sides shaped to take pendulum swing and rectangular screw sealed trunk door, the conforming concave lower moulding leading to the base with panelled front and double skirted hood, the underside with a thick wooden floor to keep it airtight, while each screw tightened surface is fitted with strips of cloth to ensure a perfect seal.
10 inch (254 mm) square silvered brass regulator dial with Arabic minutes, marked 5 to 60, outside the division ring, the subsidiary Arabic hour ring below centre reverse numbered 1-24, and signed within Earnshaw London. The upper subsidiary Arabic seconds ring supplemented with bold observatory marks every 5 seconds, the lower subsidiary Arabic hour ring reverse numbered 24 to 1. Both subsidiary dials have counter balanced hands, the hour hand rotating contra clockwise.
The very substantial five pillar (Betts ref. Type 1) movement is of the very highest quality, with an extension to the right side of the plates taking the stop work, jewelled to the escape and pallet arbors with Harrison’s maintaining power, exceedingly fine train wheels and high-count pinions. The top with dust plate and knurled fixing screws, similar to the case screws but smaller, the movement located onto the massive 2 inch seatboard with two brass edge strips, stepped at either end to guide the plates, and conventionally screw-fixed to the base pillars. Massive cast-brass pendulum support with suspension for the 5-rod zinc/steel gridiron compensated pendulum with massive bob, engraved regulation nut, and secondary fine rating ball below.
First reported in Calcutta (Kolkata) in 1999, sold by Bobinet in 2006 for £100,000;
Derek Roberts, English Precision Pendulum Clocks, 2003, Chapter 4, Thomas Earnshaw by Jonathan Betts, p.55-67, illus. fig. 14-4
The Calcutta Earnshaw. Circa 1792
A highly important George III month-going mahogany regulator with Maskelyne’s proposed hermetically sealed case and jewelled deadbeat escapement by Thomas Earnshaw, London