Equerre's were invented to set 45 and 90 degree angles in a field. Succeeded by Pantometers, which can be set at any angle.

Antique Equerre Surveyors Cross Staff- Cross finished in black lacquer with silvered dial, scale, & compass. Featuring geared adjustment, ball, & socket staff support. Complete with original Oak case. displayed on ornate, clawed Brass base. Functional with original glass. Unsigned. Dutch-made for English audience, circa 1900.

Similar Model Featured by Nicolàs de Hilster, PhD.

Antique Travelers Pantometer (Setters Compass), signed 'J. Meurthin, GEFLE'. Brass Dip Compass with original lid, glass, hand-coloured paper face, with half-blued needle. French made, circa 1840-1860.

Featured in Sweden's National Museum of Science & Technology.

Dip (Needle) Compass, also called an Inclination Compass; Invented to measure the vertical force of the Earth's magnetism. Incredibly precise scientific instruments allow for drawing maps of equal inclination (isoclinic).

Antique Brass Miners' Ring Dial by W & L.E. Gurley, circa 1870.

Featured in Harvard University's Collection of Historical Scientific Instruments.

WW2 Dipping Dial by Joseph G. Pollard & Co. Made in New Hyde Park, NY., circa 1940.

Similar Model Featured in The Compass Museum.

Trough Compasses are used to accurately align other instruments such as a plane table, theodolite etc. to the magnetic north.

WW1 Wooden Cased Trough Compass by Troughton & Simms Ltd, London, 1916.

Featured in the U.S. Geological Survey Museum.

Vintage Cold-War U.S.S.R. Military Trough Compass.

A fine array of various Button Compasses.

Featuring a Solid Gold Victorian Rotating Compass Charm, circa 1880. 9K Yellow Gold, English Made.

Featuring two small brass demonstrational dip needles, used to show the inclination of Earths magnetic fields.

Similar Models Featured at Colorado State University & Virginia Tech.