An extremely rare Schmalcalder's Patent type prismatic compass, made in London by Thomas Jones c.1826. The compass card is signed 'Thomas Jones, 62 Charing Cross, London'. Jones moved his business to Charing Cross in 1816, and remained there until he relocated to Rupert Street in 1850. The compass has a hand-drawn white coloured card, brass case with push-fit lid, prism and vane sights, and transit lock. The base of the compass has a screw-threaded mounting point for a tripod.
The colour of the compass card is very unusual - apart from the earliest Kater Mirror compasses Jones produced c.1811, almost all his compasses featured a bright green card. Very few had a white card - the prototype of Kater's design, made by Jones in 1811, has one, as does another Kater in the collection of the Science Museum in London. There do not seem to be any other Schmalcalder types made by Thomas Jones with a white card, making this compass exceptionally rare, and possibly unique.
Thomas Jones (1775-1852): Thomas Jones F.R.S., F.R.A.S. was one of the most celebrated makers of scientific instruments of the 19th century. From 1789-1796 he was apprenticed to Jesse Ramsden of Piccadilly, the most eminent scientific instrument maker of the day. Jones continued to assist Ramsden until the latter's death in 1800. With his brother, Thomas Jones worked for private customers and for the trade, in particular for Charles Schmalcalder, working on Schmalcalder's Patent prismatic compass, and also for Edward Troughton of Fleet Street. By 1806 Jones had opened his first shop in Mount Street, off Berkeley Square, in 1811 he moved to 21 Oxenden Street, and in 1816 He moved to 62 Charing Cross. Major national observatories at home and overseas ordered their principal astronomical instruments from him including the Cape of Good Hope Observatory, Greenwich Observatory, Armagh Observatory and the universities of Oxford and Cambridge. In 1824 Thomas Jones of Charing Cross was appointed Mathematical Instrument Maker to the Board of Longitude, and also became a member of the Institution of Civil Engineers. Jones was one of the founder members of the Astronomical Society, and in 1835 he was elected as a Fellow of the Royal Society. Jones devised an all-metal travelling barometer and a transit instrument for Sir Henry Englefield, a lactometer for Sir Joseph Banks, and a small azimuth compass for Henry Kater. In 1850 He moved the business to 4 Rupert Street. Thomas Jones died in 1852 in his shop, and was buried at St James's Church, Piccadilly.
Charles Augustus Schmalcalder (1781-1843) was one of the most significant figures in the development of the compass. His patent design of 1812, which introduced the idea of using an optical prism, combined with a sighting vane, to improve accuracy when taking bearings, is still in use today. Schmalcalder's innovation was a development of the work of Henry Kater. In 1811 Kater developed a design using a mirror and sighting vane. His design was then manufactured by Thomas Jones. Schmalcalder, who also knew Thomas Jones, is believed to have seen Kater's new compass at Jones' premises, and this gave him the idea for his own prismatic version. Schmalcalder moved swiftly to have prototypes of his own design made by Jones, which he then went on to patent. Winning the race to patent his innovation, Schmalcalder's compass completely eclipsed Kater's earlier design. Between 1812 and 1826 (when the patent expired) Schmalcalder's Patent compasses were manufactured by third party makers, like Thomas Jones, and sold from Schmalcalder's premises, first at 82 The Strand, London, and later from 399 The Strand, London. Schmalcalder continued in business until around 1840, with his design being used uncredited by many other makers, such as Simms, Barker, Jones, and Troughton after the patent expired in 1826. No doubt as a result of this, Schmalcalder fell on hard times, dying in poverty in 1843 and being buried in the Strand Union Workhouse cemetery.
(Much of the above information on the Schmalcalder compass is based on the extensive research and expertise of Paul Crespel at trademarklondon.com. More information on Schmalcalder, Kater and the development of the early prismatic compass can be found at the trademarklondon.com website).
Condition:
In very good, virtually 'museum', condition, and full working order. The compass finds North well. The original glass and prism are in very good condition, with an excellent view of the card through the prism. The compass card is in excellent condition. There is some wear and a few marks to the original lacquered finish of the brass case.
Dimensions: 70mm (90mm inc. prism), height: 25mm
