THE GYKOSTATIC COMPASS MARCHAND. 115 



second limb, which makes one complete rotation for each 10 degrees 

 of deviation and thus renders visible very small deviations. The 

 current for the motors of the gyrostat and of the transmitter is fur- 

 nished at 120 volts, 333 periods per second by a 16-pole motor 

 generator working on an ordinary direct-current lighting circuit. It 

 runs at a speed of 2,500 turns per minute. The motor of the gyrostat 

 is bipolar. An Anschutz compass uses normally 700 watts. Besides 

 the apparatus already described, there is furnished a short description, 

 with the necessary directions for starting the compass and regulating 

 it. Ammeters are placed in each of the three circuits, and a voltmeter 

 may be connected between any two of them. For each wire there is 

 a pair of fuses so contrived that, by means of a quick- working switch, 

 if one of the fuses fails the other may be quickly inserted. 



