THE MOST CURIOUS CRAFT AFLOAT 



233 



BEGGAR AT MAHUN, PERSIA 



these are more or less temporary de- 

 rangements, and after a certain time 

 the needle recovers its normal direction. 

 Frequently during the so-called "mag- 

 netic storms" there are electric currents 

 generated in the earth of sufficient 

 strength to interfere seriously with tele- 

 graphing and cabling. 



Were it possible to substitute some- 

 thing else for the magnetic compass it 

 would be a waste of funds, as judged 

 from the "purely practical standpoint," 

 to carry on the extensive magnetic oper- 

 ations of the Carnegie Institution of 

 AVashington. However, nothing has been 

 found as yet which "fills the bill" as well 

 as the compass, in spite of its manifest 

 defects. 



THE "gyroscope compass" 



The papers have recently had con- 

 siderable to say regarding the so-called 



"gvroscope compass." This instrument 

 is not dependent for the maintenance of 

 its direction upon the earth's magnetism, 

 but is an embodiment of the principle of 

 the spinning top. The spinning is done 

 by an electric motor, a 9-pound wheel 

 rotating about 21,000 times a minute. 

 Just as the axis of the top maintains an 

 invariable direction while the top is in 

 rapid motion, so does the axis of the 

 gyroscope remain unaltered for some 

 time in the direction originally set ; this 

 direction maybe due north and south, for 

 example. The precise advantage of this 

 instrument is. that it is unaffected by any 

 neighboring iron, and hence this sort of 

 a compass is peculiarly useful on the 

 modern steel vessels and on war-ships. 

 Instead, however, of displacing our old 

 standby, the magnetic compass, it must 

 be regarded chiefly as an adjunct to the 



