- Museum number
- 1989,0307.1
- Description
-
Long-case regulator in mahogany case with reeded pilasters on the hood and trunk corners, lower sections inlaid with brass; break-arch hood with front-opening door and gilt-brass ball finial; door in plinth allows access to the pendulum; pasted to the inside of the trunk is a sale-catalogue description of this clock and manuscript instructions for setting it up; composite dial, central gilt-brass section engraved with foliate scrolls surrounding two white enamel dials, the upper one for seconds, the lower one for hours and minutes; to the left is a thermometer and to the right a barometer; weight-driven two-week movement with geared stop-work and Harrison's maintaining power; four-wheel train terminated with Mudge gravity escapement with gridiron compensation pendulum.
- Production date
- 1790-1800
- Dimensions
-
Diameter: 27.50 millimetres (case)
-
Height: 208 centimetres (case)
-
Width: 51 centimetres (case)
- $Inscriptions
-
- Curator's comments
- Text from 'Clocks', by David Thompson, London, 2004, p. 124.
Thomas Earnshaw/ Joseph Catherwood
Longcase regulator
London, c. 1795
Height 208 cm, width 51 cm, depth 27.5 cm
From the middle years of the eighteenth century, in the age of Enlightenment, and perhaps inspired by the two transits of Venus in 1761 and 1769, a number of private observatories were set up in Britain. A particularly famous one was that which King George III had built at Kew, where he personally tested John Harrison's timekeeper H5. Less well-known was the astronomer William Larkins, whose private observatory was at Blackheath, London. For his observations Larkins would have needed a good quality telescope and a high-quality regulator to provide accurate timekeeping.
It is highly likely that this superb regulator was the one which Larkins used. There is no absolute proof of such a provenance, but the sale catalogue of 23 June 1800 listing the contents of Larkins' observatory describes 'an excellent transit clock, compound pendulum, barometer and thermometer within, in a handsome mahogany case, Earnshaw.' The name Earnshaw in connection with this clock is a perfectly logical one, for while it is signed Catherwood, the whole design of the movement and case point to Thomas Earnshaw as the maker rather than Joseph Catherwood, who is not known to have been anything more than a retailer. Compelling evidence for an early change in the name on the clock is that the dial was punched out from the back to remove an original name before Catherwood's name was added. The original name cannot now be discerned. Further evidence exists from Earnshaw himself in his 1808 publication 'Longitude. An Appeal to the Public', where he says, "The best clock I ever made, was for Mr. Larkins of Blackheath". It is very likely that this is the clock to which Earnshaw refers. There is no doubt that it is the only regulator known to survive with a dial which provides readings for both temperature and barometric pressure.
The case is of exceptional quality with reeded pilasters on the hood and trunk corners and an extra door on the plinth, which allows access to the pendulum for rating. The composite dial has a middle section of gilt-brass with floral ornament surrounding two white enamel dials, the upper showing seconds, the lower for hours and minutes. To the left is a silvered plate carrying a thermometer calibrated in degrees Fahrenheit and to the right is a mercury barometer with a Vernier scale calibrated in inches.
The weight-driven movement of two-week duration is also of fine quality, with Earnshaw's version of Thomas Mudge's gravity escapement controlled by a nine-bar Harrison gridiron compensation pendulum. This pendulum is unfortunately not the original but a modern replacement of an earlier wood-rod pendulum, which itself would have replaced one of gridiron form. This clock was without doubt one of the more important regulators made at the time and today it has the earliest example of Mudge's detached gravity escapement known to survive.
Purchased in 1989.
- Location
- On display (G39/od)
- Exhibition history
-
Exhibited:
1998-1999 04 Dec-18 Apr, London, National Maritime Museum, Arnold & Earnshaw, Pioneers of the Chronometer
- Acquisition date
- 1989
- Department
- Britain, Europe and Prehistory
- Registration number
- 1989,0307.1
