1920] on the Gyrostatic Compass 35 



The '"Brown" Gyro-Compass is shown diagrammaticallv in 

 Fig. 7. 



A is the gyro wheel in its casing B. This case is carried on 

 knife edges M in the vertical ring F, and is thus free to tilt under 

 the action of the rotation of the earth. 



The vertical ring turns in azimuth on a frictionless mounting, 

 consisting of an oil pump at the bottom of a ball-bearing m at 

 the top. 



XT is the three-phase motor that drives the oil pump. 



Fig. 8.— Gyrostat. 



The gyro wheel is the rotor of a three-phase motor, and current 

 is led into the moving system through the three sets of iron contact 

 rings R and S. These rings do not touch, but the outer set are 

 hollow, and mercury fills the space between them, so that_there is 

 little friction. 



The vertical ring is dynamically balanced by two projecting 

 weights D. 



Q is the pendulous mounting, supported by gynibal rings and by 

 the outer row of springs to take up shock. 



D 2 



