Combined Prismatic Compass & Clinometer ~ Barker’s Patent ~ Leather Case ~ c1890

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Seller: barnowl582 ✉️ (848) 100%, Location: Orpington, GB, Ships to: WORLDWIDE, Item: 132743344751 Combined Prismatic Compass & Clinometer ~ Barker’s Patent ~ Leather Case ~ c1890.

Barker’s Patent Combined Prismatic Compass & Clinometer with Leather Case - c1890.

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A Lawrence & Mayo combined prismatic compass and clinometer dating from c1890.

Patent No: 1926. - Serial No: 1340.

LAWRENCE & MAYO

Sidney Solomon Lawrence was an optician active 67-69 Chancery Lane in London. He created, together with another London optician called Mayo, the company Lawrence & Mayo (19 New Oxford Street. London. Some instruments signed L. & M . were in reality made by famous makers like F. BARKER, STANLEY or STEWARD

This Angle of Sight instrument is dual purpose in that it incorporates a prismatic compass, consisting of a silvered ring dial with a 360 degree scale, and a centimetres per metre clinometer, visible in the vertical plane. These two functions are controlled by the brass button on the side which locks the compass when using the clinometer, and vice versa.

When used as a clinometer the weighted clinometer card is released by pulling the knob at the top. Held vertically it is sighted in the same way as when used as a compass and the clinometer card read through the prism, which can be raised to suit. It can also be used to measure the slope of a surface by direct reading through the lower glass. There is a tripod or staff screw under the base plate for when it is used as a compass.

(A similar model appears in a 1919 Francis Barker catalogue, where its referred to as a ‘combined altitude instrument and prismatic compass’)

WF Stanley calls this Barker’s Combined Prismatic Compass and Clinometer. Retaining virtually all of its original black finish, it is engraved Barker’s Patent This type of instrument was often used by artillery regiments in the British army for range calculations and targeting heavy guns, and also by civil engineers. In very good condition, including the black leather case.

  • Period: 1800 to 1900
  • Type: Compass/Clinometer

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