62 VARIATION OF THE COMPASS. 



From which it would appear that it had already be- 

 gun to return from its extreme western deviation. 



Greatest Variations. 



The coasts on which the greatest deviations of the 

 needle have (until recently) been observed, are, Cape 

 Farewell, Davis's Straits, Hudson's Bay, and Baffin's 

 Bay. Between Cape Farewell and Labrador it is 

 42 and 50 ; whereas in East Greenland, which is at 

 no very great distance, the variation does not much 

 exceed one point (11 15'), and to the east of the 

 island entirely ceases. 



Daily Horizontal Variation. 



The daily horizontal variation of the needle in 

 England ranges from about six or seven minutes of 

 a degree to fifteen minutes ; the first being the quan- 

 tity due to the winter months ; the last to the sum- 

 mer months. The quantity is so inconsiderable that 

 without great care it cannot be observed. During 

 Captain Parry's expedition in 1825, the daily varia- 

 tion amounted to as many as six and seven degrees. 

 The needle was in a state of perplexing vibration^ 

 yet still following a certain order in its motion, which 

 increased as the sun approached the summer solstice. 



Extent of the Variation. 



In the northern hemisphere the western variation 

 extends over a space of 244 44', and in the southern 

 hemisphere, in the same parallel of latitude, 143 10'; 

 the balance of each circle being the utmost extent of 

 the easterly variation. 



Diurnal Variation. 



The diurnal variation, both -in the direction of Che 

 needle, and in the magnetic intensity, appears to have 

 reference to the position of the sun with regard to 



