MEASUREMENT OF THE "DIP." 23 



fixing a small pendulum to the centre of the compass directly 

 under the magnetic needle. 



To use the compass, hold it horizontally in front of the 

 eye, and note the number of degrees which the direction of 

 the line looked along makes with the magnetic north as 

 shown by the needle. The ordinary magnetic compass 

 should be divided into degrees, so that between N. and E. 

 are 90 ; E. and S., 90 ; S. and W., 90 ; W. and N. 90. 



Suppose the observer looking along the strike of a lode 

 notices that its direction is 30 from the north towards the 

 east, the direction is said to be 30? E. of N. Although the 

 prospector in his calculations will probably only note his 

 readings from the magnetic north, it may be well to remind 

 him that the magnetic north differs from the true north. 

 If the latter is required at any time it can be found by 

 noticing the shadow which a vertical post casts at noon. 



