Turning Errors of a Monitored Directional Gyroscope: A General Statement of the Nature and Magnitude During the Course of, and Immediately after Recovery from, a True Banked Horizontal Turn and the Influence of Residual Compass Error on the A.P.I.

IT is readily understood that no instrument or measuring device can be entirely free from errors duo to physical imperfections of manufacture. Gyroscopes in particular are affected in this way, requiring, as they do, complete absence of bearing friction if use is to be made of their property of preserving fixity in space of the direction of their spin axis when free from external forces. The impossibility of achieving this ideal condition results in a small degree of drift of the gyro‐axis, and detracts from the value of a gyroscope as a direction indicating device. In spite of this deficiency, in cases where steadiness of pointer reading is of prime importance, standard gyroscopic directional instruments serve a very useful purpose, provided the necessity of applying corrections at appropriate time intervals is recognized and observed. Latterly, development along the lines of automatic compensation has overcome this defect, and has led to the advent of the ‘monitored’ gyroscopic compass.