An antique brass Watson Service Petrological Microscope c.1920, engraved to the body tube "SERVICE" PETROLOGICAL W Watson & Sons Ltd, London 31156' the microscope on black lacquered stand, plano-concave mirror, substage polariser, rotating stage (cracked with losses) , body with slide in/out polariser, in it's polished wooden case. Watson's "Service" series was highly regarded for its robust build and reliability. The petrological version included accessories such as rotating stages, polarising components, and optical features suited for geology and mineralogy. The case measures 40 x 22 x 25cm (15.75" x 8.66" x 9.84") and of substantial weight at 8.2kg (18Ibs). Optics not tested for laboratory use but visually functional. W. Watson & Sons were opticians and camera makers trading from London and Edinburgh. The company was originally founded in 1837 by William Watson at 71 City Road, and the business continued at this address until 1861, when it moved to 313 High Holborn. In 1867, the name was changed to W. Watson & Son. In 1882, the name was changed to W. Watson & Sons. In 1900 the company acquired the John Browning and Co., and in 1908 the firm became W. Watson & Sons Ltd. In 1929 they published an advert in the British Industries Fair Catalogue as an Optical, Scientific and Photographic Exhibit, highlighting the manufacture of microscopes for medical, industrial, and educational purposes. Into the 1950s, the company changed their address to 25 West End Lane, Barnet, Hertfordshire, where they stayed until the late 1960s. In 1957 the company was acquired by Pye of Cambridge and ten years later, taken over by Philips. By 1970, the manufacture of microscopes was over.