WORKING WONDERS WITH A TOP 



All this is obviously only a roundabout way of say- 

 ing that the axis of the gyroscope in question is a 

 compass pointing to the true north, forced into this 

 position by the power of the rotating world itself in 

 conjuction with its own rotation, and held there in- 

 flexibly so long as world and gyroscope both continue 

 to rotate. 



Such is the theory of the gyro-compass. In the 

 practical application of the theory there is oppor- 

 tunity for the display of great inventive ingenuity. 

 German inventors have sought to solve the problem 

 by floating the gyroscope on mercury. Messrs. An- 

 schutz-Kaempfe and Martienssen have attained a 

 measure of success in this way. But Mr. Sperry 

 thinks that the same end may be attained to far bet- 

 ter advantage by giving the entire gyroscopic ap- 

 paratus the form of a pendulum, its secondary axis 

 thus being held in horizontal position by the force 

 of gravity. 



After long series of experiments, Mr. Sperry has 

 perfected a gyro-compass that is a highly efficient and 

 practical instrument; a better instrument, indeed, in 

 many ways than any magnetic compass ever de- 

 vised. In proof of practicality, it suffices to note that 

 the Sperry gyro-compass has recently been installed 

 on a number of our battleships, including the Florida, 

 the North Dakota, the Utah, the Delaware, the Michi- 

 gan, the New Hampshire, the Kansas, the Rhode Is- 

 land, the Arkansas, and the Wyoming. A Brazilian 

 battleship similarly equipped steamed out of New 

 York harbor the other day; and the largest ship in 

 commission, the Imperator, carries a gyro-compass of 



18 265 



