The pole star was recognized by the ancients as being a constant reference for determining direction. The Norsemen in the 11th century used a needle of magnetic iron inserted in a straw and floated on water to point to the pole star. Petrus Peregrinus de Maricourt invented the pivoted floating compass with lubberline and sight for bearing. The modern compass is little more than one-hundred years old..

The compass card, due to wind rose origins is older than the magnetic needle. A names of the cardinal compass points are from the ancient Nordic terms for wind direction. Variation was understood by 1800 as a problem. Edmond Halley at end of 17th century mapped lines of variation and drew isogonic lines (lines of variation) on his maps. George Graham showed that variation was subject to diurnal (seasonal) changes with variation being less in winter.

Deviation was written about in 1627 by John Smith as a problem encountered through use of metal nails in his compass box. Captain. Matthew Flinders in 1.801-2 found way to correct by use of "Flinder's Bars as did Lord Kelvin through use of Kelvin spheres. Placement of soft iron spheres at sides of compass could be used to correct deviation.

The development of the gyro compass began in 1851 when Leon Foucault used suspended cannon shot on a long wire pendulum to show the rotation of the earth as well as the inertia of the free swinging ball. By 1852 he had created the gyroscope but had trouble applying continuous power. By 1900 the electric gyroscope was invented by both Elmer A. Sperry and Anschutz-Kampfe of Germany. By 1911 gyro compasses were in use soon to be followed by gyro repeaters (selysn(sp) units) and gyro pilots. First airborne gyroscopic instruments were tried on airships.

Written by Gene Whitt