WWI British Military Rangefinder – Barr & Stroud Infantry Rangefinder No.2 (Mk III) – 1915 – Fully Functional – 90 cm Rare and original First World War military optical instrument manufactured by Barr & Stroud Ltd., Glasgow & London, one of the most important producers of precision optical equipment for the British Armed Forces. This is an Infantry Rangefinder No.2 (Mk III), dated 1915, with serial number 1936, retaining its original brass construction and military markings. Historical background Barr & Stroud rangefinders were widely used by the British Army during World War I for battlefield distance measurement. These instruments allowed officers and artillery observers to accurately calculate the distance to enemy positions, artillery targets, machine-gun nests, and advancing troops. The Infantry Rangefinder No.2 was specifically designed for: • Infantry observation units • Forward artillery observers • Trench warfare targeting • Coastal and defensive military positions They were operated by trained rangefinder crews or officers working alongside artillery batteries and infantry command units. Accurate distance measurement was essential for directing artillery fire before modern electronic systems existed. Technical details • Maker: Barr & Stroud Ltd. • Model: Infantry Rangefinder No.2 (Mk III) • Type: FT27 • Year: 1915 • Serial number: 1936 • Length: 90 cm • Base length: 80.0 cm • Material: Brass and steel construction • Optical system: Coincidence rangefinder • Original engraved military plates present Condition • Fully functional optical system • Mechanics operate correctly • Optics clear with normal age-related signs • Original patina preserved • Good overall condition consistent with wartime use and age (see photos) The instrument remains an impressive example of early 20th-century military engineering and is highly decorative as well as historically significant. Collector interest Barr & Stroud rangefinders are sought after by collectors of: • WWI militaria • Scientific and optical instruments • Naval and artillery equipment • Museum and historical displays A rare surviving First World War precision instrument with strong display presence due to its large size and authentic military history.