THE SPERRY GYRO-COMPASS IN SERVICE. 299 



eration curve, taken in stopping the wheel by reversing the power to the gyro 

 motor. If allowed to run without braking, the wheel would continue to 

 rotate for approximately four hours and, as before stated, would hold the 

 meridian for about one hour. 



During the past summer a board of naval ofScers, of which Lieutenant 

 Commander Miller was the senior member, was convened for the purpose of 

 testing all phases of the actions of the compass in service. These tests were 

 carried out at sea on the U. S. S. Worden. 



Tests under roll and pitch demonstrated conclusively that the compass 

 is free from the slightest oscillations due to the forces so impressed. 



The board wished to particularly test the compass with a view to deter- 

 mining what oscillations, if any, would be introduced by the most severe 

 changes of the speed and course of the vessel on which it is mounted. 



The results of this test can be seen from Fig. 14, Plate 1 09 . The changes 

 in speed and course were so timed as to impress acceleration pressures at 

 exactly the right point for causing the maximum increase in oscillation. As 

 will be seen from the figures, the maximum amplitude of oscillation from the 

 meridian was three-fourths of a degree. This three-fourths of a degree is 

 really the summation of three impulses each superimposed on the other. If 

 these impulses had not been timed so as to add to each other the oscillation 

 would not have exceeded one-half a degree. 



Repeated tests on battleships and submarines have demonstrated con- 

 clusively that roll and pitch do not cause the slightest deviation of the 

 compass. 



This information is, of course, of great value in considering the use of the 

 compass in maneuvering ships in fleet or division formation, and proves con- 

 clusively that the most severe oscillations which can be introduced are hardly 

 appreciable. 



Up to the present time the adoption of the Sperry gyro-compass has 

 proceeded without encountering that manifestation of the laws of inertia 

 known as "conservatism." The author believes that, by reason of the 

 results achieved, this will continue to be the case. 



DISCUSSION. 



Rear Admiral Bradley A. Fiske, U. S. N. (Communicated): — I have 

 glanced over the paper of Mr. Gillmor called "The Sperry Gyro-Compass in 

 Service." Mr. Sperry's gyroscope compasses are fitted in the Florida, and I am 



