On a Mass of Meteoric Iron. 



409 



the question of the distribution of aerolites. Had we such a 

 map, we could judge at a glance whether meteoric falls were 

 generally pretty uniform in their distribution over the earth, 

 according to Mr Greg ; or whether there are any signs of the 

 local aggregation of these bodies in particular districts, as in 

 the two so-called meteoric zones of Professor Shepard. 



Have Meteoric Falls any relation to Terrestrial Mag- 

 netism ? — We already possess maps, giving us the rain-fall 

 over the world ; and what a pleasure it is, when studying 

 them, to be able to turn to other maps of allied phenomena, 

 as, for example, the map of the winds, and to see at once how 

 these different agencies act and react upon each other, and 

 how the one map helps to explain to us the other. If we had 

 our map of the aerolite falls, could we turn to any other map 

 in our physical atlas that would help us to understand them 

 any better? I cannot tell — but would be greatly interested 

 in examining and comparing with it the maps illustrating the 

 difficult subject of our terrestrial magnetism, and would be 

 anxious to see whether the one threw any light, or appearance 

 of light, at all on the other. To enable me the better to judge 

 of this, I would carefully distinguish all metallic from earthy 

 meteoric falls, and would be curious to observe whether the 

 apparently irregular scattering of the former over the world 

 could be seen to bear any particular relation to the various 

 centres of greater magnetic force. 



There are four poles or maxima of magnetic attraction known 

 to exist in our earth, a stronger and a weaker, in the northern 

 hemisphere ; and also a stronger and a weaker pole in the 

 southern hemisphere. Supposing I have correctly stated these 

 views of our terrestrial magnetism, it does seem interesting 

 to find an observer like Professor Shepard coming to the con- 

 clusion, from entirely different data, of the existence of the 

 two meteoric zones, which at once attract me, by their position 

 appearing to bear some relation to these northern poles of 

 magnetic force. He tells us, he finds the meteoric zone of the 

 old continent rather strangely translated farther to the north 

 than that of the American continent ; this seems also to 

 show a relation between terrestrial magnetism and these 

 meteoric falls, as it is stated that the northern pole of mag- 



