Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)




Although Foucault did considerable work on the behavior of rotating bodies, the Foucault gyroscope or gyroscopic compass appears to have been suggested by Lord Kelvin in 1883. Essentially this is a rotating body suspended with its axis of spin free to turn in a horizontal plane. The first commercial gyrocompass, the Anschuetz-Kaempfe model, was patented in 1908. It was followed in 1911 by the Sperry gyrocompass. These two are the most important commercial gyrocompasses although several improvements and modifications have been patented. The Anschuetz compass used mercury to suspend the direction-seeking element. This element contained three rotors, the main north-seeking one and two smaller ones. The axes of rotation of the small rotors were at right angles to that of the main one, all being in a horizontal plane. The small rotors were spun in opposite directions so their angular momentum cancelled out as far as affecting the direction-seeking action was concerned but still served to stabilize the floating element. A later model of this compass used two rotors spinning in the same direction with their axes of rotation separated by about 45 degrees in a horizontal plane. Here the north-south axis lay halfway between the axes of rotation of the rotors and again the east-west components of angular momentum cancelled out in their effect on the direction-seeking action but still served to stabilize the floating element. The early Sperry compass used a single rotor with a spring suspension system and an electric follower unit to drive the suspension around to keep any torque-inducing tension in the springs at a minimum. If there were no damping present in the supporting mechanism of the direction-seeking element in a gyrocompass, and, if the element were not initially oriented with its axis of spin pointing north, this axis would oscillate about a north-south line, the motion being essentially simple harmonic motion due to the interaction between the spin of the rotor and the spin of the earth. For a nautical compass, any practical system of supporting the direction-seeking element will transmit some of the movements of the ship to the element. For this reason, it is desirable that the period of oscillation of the element be large as compared to the period of any movements of the ship in order to reduce the effect of such transmitted motion. Theory indicates that a compass with a period of 84 minutes would swing ‘deadbeat’ to the correct reading after any change of course. For these reasons, commercial gyrocompasses have a large period, 70 minutes being mentioned as one value. While it would be interesting as a demonstration to watch a gyrocompass oscillate about the north and settle down pointing north, a 70 minute period of oscillation is reason enough to rule out the use of a commercial gyrocompass for this purpose. To be effective for demonstration purposes, a gyrocompass should have a short period, preferably on the order of five minutes or less. It should also be possible to damp out the oscillation and have the compass pointing north. This thesis is concerned with the construction and operation of a short period gyrocompass suitable for demonstration of the “gyrocompass effect”.

Library of Congress Subject Headings

Gyro compass


Includes bibliographical references



Number of Pages



South Dakota State University


No Copyright - Non-Commercial Use Only