A very rare example of an unusual variant of the Greencard-type prismatic compass, made c.1845, almost certainly by Henry Barrow. With a hand-drawn green compass card, bronzed-finish brass case, prism and vane sights, transit lock, and manual brake. Although there are no makers marks, this very uncommon type of compass is known to have been produced by only two makers, Henry Barrow (1790-1870), one of the finest instrument makers of the mid-19th century, and Cary of London. Barrow and Cary were associated, as Henry Barrow worked on the repair of Cary's famous 'Great Theodolite' and other instruments for Sir George Everest during the Survey of India in the 1830's.
The compass has a transit locking mechanism operated by a slide at the side of the case, and a card brake operated by a push-button. There is a folding slit sight on one side and a folding 'A' frame complete with thread sighting line and a 90 degree prism. The compass card is graduated to eight points and to 360 degrees, with a jewelled pivot cap.
This partcular compass design is notable for the prism being located on the long sighting vane, rather than in the more conventional position of a housing attached to the edge of the compass case. A very well made, high quality instrument, this compass was undoubtedly the work of one of the best maker's of the period. An almost identical example, made by Henry Barrow, can be seen in the collection of the Royal Museums at Greenwich - https://www.rmg.co.uk/collections/objects/rmgc-object-42637
Henry Barrow (1790-1870): was one of the finest British scientific instrument makers of his time. He may have been apprenticed to George Dollond or Edward Troughton, as he is known to have worked for both of them before 1829. From 1830-1839 he was Mathematical Instrument Maker to the Surveyor of India, working very closely with Sir George Everest, maintaining the complex scientific instruments that were vital to the work of the Great Survey of India. After returning to England, Barrow took over the business of Thomas Chales Robinson at Devonshire Street, London from 1842. From 1845-c.1860 he traded as H. Barrow & Co. from premises at 26 Oxenden Street, London. He is known to have produced compasses, theodolites, and other scientific instruments during this period, supplying them to both the East India Company and the Great Survey of India. He also made compasses for the Admiralty, some of which were used in Arctic expeditions during the 1840s. During his time with The Great Survey, Sir George Everest had praised Barrow's work on the Cary Great Theodolite: 'I must do the artist (Barrow) the justice to say that for excellence of workmanship, accuracy of division, steadiness, regularity, and glibness of motion, and the general elegance and nice fitting of all its parts, not only were my expectations exceeded but I really think it is as a whole as unrivalled in the world as it is unique.' Henry Barrow was made a Fellow of the Royal Astronomical Society in 1849, and retired around 1860. His long career had made him a wealthy man, and he left an estate valued at more than £65,000.
Cary of London: William Cary (1759-1825) produced numerous scientific instruments, including mechanical calculators, measuring instruments, telescopes, microscopes, compasses, and survey equipment. William had three brothers, one of whom, John, was a map maker who worked with him. Cary had learned the skills of instrument making as an apprentice of Jesse Ramsden (1735-1800). After William's death in 1825, the firm was taken over by Charles Gould, who many have trained under Cary. The company continued trading for almost 100 years, being run by various members of the Gould family, including Chalotte Hyde Gould (c.1797-1865). They became well known as retailers of globes and other scientific and mathematical instruments. Around the time of the first world war Cary were trading from premises at 7 Pall Mall, London.
In very good condition, and full working order. The compass finds North very well. The glass, sighting vane, and prism are all in very good condition. The view of the card through the prism is excellent. The compass card is in very good condition. Both the manual brake and transit lock are working perfectly. There is minor wear to the original bronzed finish of the brass case.
Dimensions: 100mm diameter, case 18mm, sights (height above glass) 85mm