Victorian Cased Mercury Trough Type Artifical Horizon by John Crichton of London

For sale, a cased mercury trough type artificial horizon by John Crichton, London

This example is comprised of a wooden trough with an ingenious system for filling the basin. The centre of the trough has a hole to the centre with a bone disc surround. This hole is connected through the base to the larger hole at the rim of the trough into which the threaded bone funnel is screwed as a means of pouring the mercury. The mercury would then fill the trough from the underside and would avoid any spills of the precious substance. A lip to one of the corners would then allow the mercury to be transferred back to the bottle with the same funnel inserted into the bottle.

The boxwood mercury bottle has both a stopper lid which pulls directly from the top and a secondary plug inserted into the lip for additional protection.

The black painted metal horizon roof is strongly constructed with glass viewing panels either side and is engraved to “Crichton, London” on one side.

All of the separate parts are enclosed in a superbly patinated mahogany box with an equally ingenious fitted interior to ensure safe stowage during transit. It has the original lock and key with additional hook and eye fasteners and and a blank brass cartouche on the lid. The box also contains a secondary label to the company of Lilley & Reynolds who would have retailed this as a second hand item around the 1930’s.

The history of the artificial horizon can be traced back to the sixteenth century but developments were largely popularised in the eighteenth century by John Hadley, John Elton and by the famous instrument maker, George Adams, the latter of whom is merited in 1738 with inventing the mercury trough of which this is an example. It was devised as a means of navigation when the horizon was obscured by darkness or through the effect of inclement weather.

Its principle was based upon the first law of optics, that the angle of reflection from a mirror is equal to the angle of incidence, therefore a sextant would be employed to measure the angle between the sun or the stars and their reflection on the mercury contained in the metal trough. Although the instrument was dogged by criticism relating to the tremoring of the mercury when excessive movement was involved, it must have proved popular enough owing to its continuing manufacture.

Apprenticed in 1820 to Benjamin Messer of The Minories in London, John Crichton is listed as trading in his own right by 1831 at 32 Fore Street, Limehouse, London. He moved after three years to 112 Leadenhall Street, London where he advertised himself as instrument maker to the Honourable East India Company and to Trinity House, perhaps not surprising given the close proximity of his premises to both establishments. He was an exhibitor at the Great Exhibition of 1851 where he was awarded a prize medal for sextants and drawing instruments and the firm continued to trade beyond 1864 as John Crichton & Son. Surprisingly little more is known of Crichton although his marine instruments are widely renowed for the quality of their manufacture.

Lilley & Reynolds, the second hand retailer of this piece, were formed from a departure of the partnership of George Lilley & John Wilson Gillie in 1911. By the 1930’s, some of the Lilley family in London departed to form a new partnership in around 1934.

A fine example of an early nineteenth century artificial horizon with some interesting and unusual features. Circa 1840.