WORKING WONDERS WITH A TOP 



with all these difficulties. It may be placed far down 

 in the depths of the steel hull, away from danger of 

 shot and shell. In fact the chief compass is so placed 

 in our recent battleships, being connected by wire 

 with various smaller repeating compasses whi-ch may 

 be distributed about the ship at any desired place. 

 Thus located, deep in the hold, surrounded by struc- 

 tures of steel, near guns and under turrets that are 

 likely to shift position, the ordinary magnetic compass 

 would be absolutely useless. But the new compass 

 operates under these conditions precisely as it would 

 operate on the "Carnegie" a ship which, as .perhaps 

 the reader is aware, is composed of wood, and the en- 

 tire structure of which, so far as possible, has been 

 equipped with non-magnetic appliances in order that 

 it may exert no disturbing influence on the compass, 

 and thus may be used for a survey of the conditions of 

 the earth's magnetism in hitherto uncharted seas. 



Add that the new compass, as installed in our bat- 

 tleships, seeks the true north with a force hundreds 

 of times stronger than that which impels the magnet- 

 ized needle of the ordinary compass to point toward 

 the magnetic pole, and we gain a still clearer impres- 

 sion of the preeminent qualities of this revolutionary 

 apparatus. 



But what, it will naturally be asked, is the principle 

 on which the new compass works? What non-mag- 

 netic force is there that can conceivably cause a sus- 

 pended bar of metal to point rigidly to the north how- 

 ever its supports may be shifted? The answer is that 

 the force which produces this extraordinary effect 

 is due to the rotation of the earth itself, The appara.- 



257 



