as when entire, viz. that the current would still preserve its defi- 

 nite direction through the separate pieces as when entire ? Such 

 is the fact ; each portion of the fractured magnet is a magnet 

 perfect in itself, i. e. each has a north and south end correspond- 

 ing to their united position. Similar effects ensue from the sub- 

 division of one of these fragments into any number, however 

 great ; and if reunited, by placing them together again in the 

 same position, the result would be the same : that such would 

 be the case is very evident, as the separation of the magnetic 

 bar, provided it be effected without injuring its magnetic proper- 

 ties, only diminishes the length of the channels, not changing 

 or altering the natural direction of the currents imparted to it 

 originally. 



A similar process of reasoning, derived from the same principle 

 of action, will show that two similar poles must repel one another, 

 and that two dissimilar poles must attract each other, owing to 

 the tendency of the circulating currents to obtain a free passage. 



The intensity of the action of the currents must be as their 

 density ; and if we assume that the whole of the circulating cur- 

 rents round the magnet, within a certain limit, are converged 

 into the polar focus, their intensity must increase towards that 

 point, inversely as the square of the distance ; like any other 

 fluid, air, water, or steam, which may converge to, or diverge 

 from, a central passage. Consequently we can determine the 

 resultants of the forces which may act upon a magnetic needle 

 when its centre is situated in different directions relatively to the 

 axis of another magnet ; and what will be its movements, and 

 what its final position of equilibrium. As the sketches exhibit 

 the various effects, and as the correctness of the above is so 

 easily proved by very simple experiments, we need not enter into 

 any tedious details, but beg references to the Plates for ocular 

 demonstration, which it is hoped will be found more clear and 

 explanatory than any written description. Let us proceed to 

 examine the effects of a magnet placed in a globe, as shown in 

 Plate I. 



In placing needles round this globe, we find them arranging 

 themselves in the exact order which they keep on the terrestrial 

 globe, both as to dip and direction ; and as there is nothing to 

 disturb them on the wooden globe, their positions in the curves 



