This is a rare and unusual French military rangefinder and compass instrument, made by Huet of Paris c.1911-1920, and used during WW1 by French artillery units. This type of instrument was known as a Sitomètre (or sitogoniomètre) in French and Sitometer in Swiss German. The name comes from the French expression for elevation angle which is called angle de site while the azimuth angle is called angle de gisement. The angle of elevation of the target can be viewed through a small window when the case is held vertically, while the bearing from magnetic north (Decigrade scale) can be read through a separate window when the case is held horizontally.
The instrument has an aluminium case (with the serial no. 1413), containing the rangefinder or Sitometre elements and the compass. The case carries the maker's mark, 'Huet, Paris' and is also labelled 'Decigrades'. This term refers to a French military system of compass bearings. Around the time of the start of WW1, France was experimenting with the use of milliemes (6400 in a circle) for use with artillery sights instead of decigrades (4000 in a circle). Britain was also experimenting with milliemes, to replace degrees and minutes. 'Mils', as they became known, were adopted by France, although the earlier decigrade system also remained in use throughout World War I. The United States, which copied many French artillery practices, was one of many countries which also adopted the 'Mils' system.
The compass itself is tiny (just 15mm diameter), but a very well made instrument, with a jewelled pivot and delicate needle. The rear of the case features a ruler marked in centimetres, and a scale intended to be used with 1/80,000 scale French military maps.
The compass is in good condition, full working order, and finds North well. The Sitometer/Rangefinder is in good condition and working order, with all the viewing windows clear and the scales legible. The spirit level element is in good working order. The aluminium case is in good condition, with just the usual signs of wear and use. The original fitted leather case is in good condition.