A very rare early prismatic Schmalcalder-type sighting compass. According to compassmuseum.com, this compass appears to be the 'missing link' between the Schmalcalder compasses of the early 1800's and the later Verner's type prismatics that started to appear towards the end of that century. Although unsigned, it seems very likely that it was made by Francis Barker, possibly as early as the 1840's. The compass has a large and very solidly built brass case, green card, jewelled pivot, prism, transit lock and manual brake. It is almost identical in size to the Schmalcalder compasses produced from 1812 onwards, the main differences being the hinged lid, riveted thumb loop, and engraved sighting line in the lid glass.
There are several intriguing markings to the base of the compass: a 'broad arrow' with the letter 'D' on either side, a serial number 'A.860', and a faintly scratched inscription 'Applied Geology, RMIT'. These markings show that at some point the compass was in Australia, as the broad arrow markings are those of the Australian Department of Defence from 1900 onwards, and RMIT is a University in Melbourne, founded in 1887. The compass itself was certainly made much earlier than 1900, so it must have been acquired by the Australian military sometime after the turn of the century. Further details of this compass can be found in the Francis Barker section at compassmuseum.com.
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.
(For more information on Schmalcalder, Kater and the development of the early prismatic compass, see Paul Crepsel's excellent trademarklondon.com website).
In very good, original condition, and full working order. The compass finds North well. The transit lock and manual brake are both working well. The case, card, glass and prism are all in very good condition. Marked on the base with the Australian military 'broad arrow'.