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 magnetism founded by direct experiment, the North 

 end is the attractive and the South end is the repulsive, or in 

 plainer language, that the magnetic fluid or currents move to- 

 wards the north, enter into the axis, through which they pass, 

 then issue out from the south pole and encircle the globe to com- 

 plete their circuit (as indicated by the direction of the needles, 

 and illustrated by the arrows in the following sketch) ; — we 

 ought to be able to trace their effects on all substances within 

 the limits of our observations. 



If the earth be a magnet, as we have endeavoured to prove, it 

 must produce the effects observed ; if it be not a magnet, it pos- 

 sesses a property identical in its results to one ; therefore all we 

 require in our investigations is the knowledge of the law of these 

 actions, as the name of the primary cause of the action cannot 

 have a material influence on our researches. If we continue to 

 call it gravitation, we must add to it a property which was not 

 applied to it before, viz. polarity, — call it magnetism, and the 

 term embraces all we require in astronomy as well as in geology. 



Let us suppose a bar, having been made magnetic, to be placed 



