16 LIGHT SCIENCE FOR LEISURE HOURS. 



The declination was discovered, independently, by 

 European observers in the thirteenth century. 



As we travel from place to place, the declination of 

 the needle is found to vary. Christopher Columbus 

 was the first to detect this. He discovered it on the 

 13th of September, 1492, during his first voyage, and 

 when he was six hundred miles from Ferro, the most 

 westerly of the Canary Islands. He found that the 

 declination, which was towards the east in Europe, 

 passed to the west, and increased continually as he 

 travelled westwards. 



But here we see the first trace of a yet more singular 

 peculiarity. I have said that at present the declina- 

 tion is towards the west in Europe. In Columbus's 

 time it was towards the east. Thus we learn that the 

 declination varies with the progress of time, as well as 

 with change of place. 



The genius of modern science is a weighing and a 

 measuring one. Men are not satisfied nowadays with 

 knowing that a peculiarity exists ; they seek to deter- 

 mine its extent, how far it is variable whether from 

 frme to time or from place to place, and so on. Now 

 the results of such inquiries applied to the magnetic 

 declination have proved exceedingly interesting. 



We find, first, that the world may be divided into 

 two unequal portions, over one of which the needle has 

 a westerly, and over the other an easterly, declination. 

 Along the boundary line, of course, the needle points 

 due north. England is situated in the region of 

 westerly magnets. This region includes all Europe, 



