THE STEAMBOAT 



2QI 



Magnetize another needle by rubbing the point on the south 

 pole and the eye end on the north pole of the magnet. Cut 

 two thin pieces of cork from a stopper. Float the corks in a 

 pan of water. Put a needle on each cork. In what position 

 do the needles come to rest? Do the points of both needles 

 point in the same direction ? Can you explain ? 



3. Set the compass on a level table and notice the direction 

 in which the needle points. Place pieces of iron and steel on 

 the table near and see if the needle is affected. Try a magnet. 



Gyro-compass. Recently there has been invented a new 

 type of compass, called the gyro-compass, which is being 



Ghss 



Compai 

 'Cord 



Mercury 



FIG. 115. Section of gyro-compass. 



used commonly, especially on battleships. The gyroscope 

 is a wheel mounted on an axle inside of a frame, which tends 

 to rotate in the same plane in which it started. If the wheel 

 is a large one, the strength of a man is not enough to change 

 its plane of rotation. In the gyro-compass the wheel is 

 caused to rotate in a north and south plane at a high rate of 

 speed by means of a motor. The gyroscope is floated in a 

 bowl containing mercury, so that the wheel keeps rotating 



