494 Geology and Magnetism. 



The general direction of magnetic curves and meridians 

 converge at the poles of the earth, preserving notwithstanding 

 their deflections and undulations from various local causes, 

 a remarkable degree of regularity. 



" Numerous fruitless investigations have been made with the view 

 of ascertaining the position of the magnetic pole, as if that must be 

 a mathematical point. 



Any person who has had some experience with the action of 

 fluids, whether water, air, or electric, converging towards or diverg- 

 ing from a central passage, must know that they cannot be forced 

 into a mathematical point, there must be a limit to their compres- 

 sion or density ; nor can it be expected that every individual cur- 

 rent should retain its exact radial course towards the focus, and 

 much less when diverging from it. Hence, from analogy and ob- 

 servations, the narrowest limits that we can assign to the polar axis 

 to which the magnetic currents converge and diverge are, perhaps, 

 the areas bounded by the arctic and antarctic circles. 



Numerous observations have been made in the equatorial regions, 

 indicating both east and west variations in the same meridian of 

 only a few leagues in extent ; and numerous other experiments and 

 observations may be quoted to prove that the direction of the needle 

 does not necessarily point towards the centre of convergence of the 

 individual current which moves it, but in the direction of the result- 

 ant, viz. the compound of the primary and local currents — the dia- 

 gonal of the parallelogram of the two actions. The local disturbing 

 force being a variable quantity subject to perpetual fluctuations, it 

 follows as a consequence that the variations of the direction must be 

 uncertain, and therefore not within the power of any formulae to 

 know their periodical amount. 



In the above, our observations have been principally confined to 

 the magnetic needle ; but as it is proved that all matter is more or 

 less affected by the magnetic fluid or current, and since we cannot 

 withhold our conviction, after tracing the curves which the needles 

 form within, on, and above the earth, that the globe is a magnet, 

 i. e. that its axis is magnetic ; and according to the law of magnet- 

 ism founded by direct experiment, the North end is the attractive 



