— 107 — 



« Suppose now the needle to dip to the several positions which I have shewn in 

 fig. 1 the pole would have, if it were in revolution. With the pole near the posi- 

 tion y, where I have shewn it was at the beginning of the 18 th century, the dip 

 would be (fig. 2) 15°; but this is the complement of the real dip at that time, which 

 was 75.° 



«With the pole at the position u, where it was about 1576, the dip would be 

 about 18° 10'; but this is the complement of 71° 50', the actual dip at that time, 

 as found by Norman. 



« With the pole at the position %, where it was about 1833, the dip would be 20°; 

 but this is the complement of 70°, the true dip at that time. 



«With the pole at the position s, where it was in 1866, the dip is 22°; but 

 this is the complement of 68°, the real dip at that time. 



« And to look into the future, with the pole at z, its farthest position from London, 

 where it will be about the middle of the 20 th century, the dip is 25°, which is the 

 complement of 65°. This I hold will be the least angle of dip, from which time it 

 will begin to inerease until the pole has reached y, when the dip will be at a maxi- 

 mum. Thus we have at London the range of the dip 10°, from 75° a maximum 

 to 65° a minimum. Now we know that in 1680 the dip was 73° 30' and approach- 

 ing a maximum, which it reached early in the 18 th century. Ali this is fully 

 borne out by snpposing that the magnetic pole revolves round the pole of the earth 

 in about 500 years, as was proved by the declination. 



« But to return to figure 2. Ma, Mv, M6, Mt represent the actual directions of 

 the dipping-needle at London about 1720, 1576, 1834, and 1866. The needle being 

 a dipping-needle, and the universal belief being that its north pole is attracted to 

 the north magnetic pole of the earth, it ought certainly to be drawn to point to 

 the north end of the earth; but so far from this being the case, it seems to be re- 

 pelled from it, and repelled it actually is, I hold. 



« There comes then this very naturai inquiry: Have we for hundreds of years been 

 maintaining that the end of the needle which is directed to the north is the south 

 pole of the needle, and upholding that which is the very opposite of fact ? Every 

 unprejudiced mind will admit that it must indeed be so. Indeed, the facts when 

 properly understood, are in full accord with the great magnetic truth, that like poles 

 repel, unlike attract. 



« If the dipping-needle be taken to the Arctic Regions, it will be found in one 

 locality to point to the ground, to be nearly perpendicular. It should be borne in mincl 

 that Sir James Eoss ne ver found it truly perpendicular, which its|lf would tend to 

 shew that the magnetic power was not in the earth. If the dipping-needle is re- 

 pelled from the pole at London, mudi more will it be repelled in Boothia, and it 

 is repelled as mudi as it possibly can be. The north end of the needle is repelled 

 from the pole, which is in the atmosphere, and the south end of the needle is as 

 much attracted by the same pole; and this is as it should be, the north pole of one 

 magnet attracting the south pole of another. 



« If the north end of the needle is a south pole, as it points to the ground, this 

 should be by an attraction. If it is attracted, it is attracted by something in the 



