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 ? 1 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- 
