376 Introduction to the Study of Science 



its plane of rotation. This property of the gyroscope gives 

 it an indefinite number of uses and makes it most interesting 

 for experiments. 



The gyro-compass in the form now used comprises three 

 wheels with spindles, each wheel with its spindle being made 

 from a single piece of flawless nickel steel and mounted 

 on ball bearings. Each wheel revolves 

 at the rate of 20,000 revolutions a 

 minute. The motive force is supplied 

 by a small electric motor. When the 

 gyro-compass is properly set, it retains 

 its direction as north and south in spite 

 of the magnetic field of the earth or 

 magnetized bodies, and in spite of 

 every possible motion and position of the 

 ship. The readings are transmitted to 

 any place on the ship and are shown on 

 FIG. 134. A simple dials in the same way as are those of the 



gyroscope. , . 



magnetic compass. 



Other applications of the gyroscope. The gyroscope has many 

 suggested and attempted applications besides the gyro-compass. 

 Cars have been devised to run on a single rail, retaining their 

 balance by means of the gyroscope. Monotrack automobiles 

 have been made in a similar way. The gyroscope has also been 

 utilized in the construction of stabilizers for airplanes (page 

 399). All such applications are still in the experimental stage. 



167. The chronometer. The chronometer, a time-meas- 

 urer, is just an accurate clock, the error of which is known and 

 taken into account in making the daily reading. A chronometer 

 runs uniformly, which is more important than that it should 

 be regulated perfectly. Why? The time kept is usually that 

 of the prime meridian. This enables the navigator to calculate 

 exactly the longitude of his vessel east or west of the prime 

 meridian. For example, a ship is at a point where the sun 

 crosses its meridian at two o'clock by the chronometer. Is 



