An extremely rare French artillery or survey compass dating from c.1894, invented by Camille Rossignol, a French officer and firearms expert. Captain Louis-Camille Rossignol (1851-1943) was a French officer and inventor, who served as 'Chef Armurier' with the 106th Régiment de Ligne in Châlons-sur-Marne. He is best known for designing an improved military compass system ('Militaire Perfectionnée'), which he patented in 1894. This instrument was in use from the 1890s to the 1930s, and was still being offered by Société des Lunetiers (S-L) in their 1932 catalogue. Rossignol also invented automatic rifles and a machine-gun. He was awarded several decorations (the Médaille Militaire, the Médaille Coloniale, and the Légion d'Honneur) for this work and for his military service in North Africa.
Rossignol patented two compass systems. The first one, dating from 1885, included a clinometer as well as a compass and was known as the Boussole militaire devant servir à diriger les troupes et au levé des plans - Military compass for leading troops and survey tasks. The second instrument, dating from 1894, was the Boussole militaire perfectionnée - Improved military compass. It is a complex and rather unusual design which features a mirrored lid, with the mirror automatically held at an angle of 45° by means of a spring and a triangular cam. It also has a boom that includes the front element of the sight and two rulers. The sight's rear element is a notch in the housing of the compass bearing setting screw. The right-hand side ruler is marked with a distance measuring scale (1/80,000, the scale generally used in French military maps at the time). The left side is a ruler marked in millimeters. The zero reference point of both rulers is located in the compass' centre, so that the divisions read 40 to 100mm and respectively 3 to 8 km. The compass capsule rotates, has a transparent base window made of horn, and a cross, one arm of which is painted black.
This compass has the maker's mark 'C. Rossignol, Chef Armurier, Bte. S.G.D.G.', on the top of the lid, and the serial number '52' on the rear sight. The low serial number shows that this compass was one of the first to be made, very probably around the time of the patent being filed in 1894. A very well made compass, with a jewelled pivot, blued needle, nickel plated brass case, and mirrored lid. It comes with its original leather case.
To take a bearing, the reflection of the compass needle is viewed in the mirrored underside of the lid, and the compass capsule is rotated until the black cross arm lies under the North pointer.
Further details of this type of artillery compass and the work of Camille Rossignol can be found at the excellent compassmuseum.com website.
The compass is in good condition, working order, and finds North well. The small compass bearing setting screw is missing from the rear sight housing, but this does not affect the functioning of the compass. The original leather case is in quite worn condition and has shrunk so that it no longer fits the compass.