WORKING WONDERS WITH A TOP 



1851. His experiments consisted of spinning a gyro- 

 scopic top, swung in gimbal rings allowing it freedom 

 of motion in all directions, in an ordinary room for 

 long periods continuously. The axis of the gyro- 

 scope retains its position in space, but inasmuch as the 

 motion of the earth constantly changes the position in 

 space of the room in which the gyroscope is suspend- 

 ed, the axis of the top seems slowly and regularly 

 to swing about, as gauged by the walls of the room. 

 The degree of shift and time required to describe a 

 certain arc accord perfectly with what would be cal- 

 culated on the supposition that the gyroscope itself is 

 stationary and the earth in rotational motion. Of 

 course no one had doubted that the earth really does 

 rotate, but Foucault's demonstration was none the 

 less interesting and spectacular. 



While Foucault's experiments with the gyroscope 

 were widely heralded and aroused great interest in 

 the scientific world, they did not lead immediately; 

 to any practical applications of the gyroscope. The 

 first successful attem'pt to utilize the principle of 

 gyroscopic action in a practical way was made many; 

 years later by Lieutenant Commander Obry, an Aus- 

 trian naval officer -who used the gyroscope as a means 

 of directing a torpedo. It is said that prior to the use 

 of this device the "torpedo was little more than a 

 possibility in warfare, but since that time the gyro- 

 gear has been very highly developed and has been the 

 most potent factor in making the torpedo an efficient 

 instrument of war." 



Subsequently attempts were made by a number 

 of experimenters to utilize the gyroscope as a stabil- 



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