and Remarks on the Theory of Magnetum, 27 



compass needle ceases lo act, in the most northern latitudes, it 

 * is because the magnetic influence there is feeble and unequally- 

 supplied, and not because the needle is then placed over the 

 very seat of magnetism. And that the cause of the needle'« 

 pointing due north and south when near the Equator without 

 any diurnal variation is, because it is there always fully acted 

 upon by that combination of light, heat and electricity, or the 

 component parts of those bodies, that may produce the mag- 

 netic fluid ; and which are so abundantly and constantly gene- 

 rated around the Torrid Zone ; and which ever exist there more 

 or lessj in such force as to render the direct diurnal influence of 

 the sun comparatively inferior upon the compass needle, and 

 therefore incapable of producing much daily variation. 



It is evident that there must be an everlasting emanation of 

 caloric, light and electricity from the Equator, verging to the 

 north and south poles of the earth. And it is obvious, that 

 whether they are distinct bodies, or only states of bodies, that 

 the sun is the great agent that produces these phenomena, or 

 regulates their rpovements. And, as this must create a conti- 

 nual Jlood of light, heat and electricity, advancing in the direc- 

 tion of the meridional lines to the north and south, and pervad- 

 ing the whole of the atmosphere and surface of the globe ; and 

 as the magnet is attracted and repelled by these bodies, accord- 

 ing to their various modifications, it is not perhaps unreasona- 

 ble to conclude that it is highly probable, that the unceasing 

 motion of those bodies from the central line of the earth to the 

 poles, may be the principal cause of most of the phenomena that 

 are connected with the polarity of the magnetic needle. 



The property which Mr Barlow's plate possesses, of causing 

 the needle to continue its action beyond the degree of latitude 

 where it would otherwise cease to act, appears to me to be a far- 

 ther confirmation of this view of magnetism, as iron seems to re- 

 tain always more or less of the magnetic fluid, or something very 

 analogous to it, and the rectifying plate will therefore for a time 

 supply the deficiency at the poles of the earth. 



If this view of this branch of magnetism is correct, it would 

 not be difficult to conceive why a magnetic needle should assume 

 a position parallel to the magnetic meridian, or nearly parallel 

 to the true meridian of any part of the earth, as it would, being 



