78 



THE GEOLOGIST. 



upon marine and fresh-water life, and, as might be expected, the presence of this 

 substance was found to be highly injurious to it, so that the animals quitted the 

 peroxide of iron as speedily as conditions would permit." 



Where these experiments ever put on record? If -so, where? If not, can 

 you tell me what was the nature of the experiments? Information on this 

 subject will greatly oblige, yours truly, W. P. 



REVIEWS. 



The Coal-Melds of Great Britain : their History, Structure, and Duration. With 

 Notices of Coal-Fields in other parts of the world. By Edw. Hull, B. A., 

 of the Geological Survey of Great Britain. London : Edw. Stamford, 

 Charing Cross : 1860. 



This is a small but extremely interesting and valuable book — valuable chiefly 

 however, for the consideration of one topic — the duration of the produce of 

 our coal-fields. When we look at the fact that of the ninety-five millions of 

 tons now raised for the supply of the whole world, the British Isles alone con- 

 tribute seventy-five millions ; and that our home consumption also, is not only 

 enormous, but perpetually on the increase — the vital character of the question, 

 in a national point of view, is strikingly apparent ; and Mr. Hull's statements, 

 brief as they are, will be read with great interest even by those who are not 

 geologists. 'While we have a good deal of information given us of the general 

 character of the strata, physical geology, and fossils of our own, and the principal 

 foreign coal-fields, in a very condensed form, all these matters are brought 

 to bear upon the one important point — the exhaustion of our coal-mines. 

 The results which Mr. Hull has arrived at are briefly given in his own recapitu- 

 lation, and are as follows : — 1. There are coal-deposits in various parts of 

 England and Wales, all at depths down to nine or ten thousand feet. 2. 

 That mining is possible to a depth of four thousand feet, but beyond this the 

 high temperature will prove a barrier. 3. The temperature of a coal-mine at a 

 depth of four thousand feet will probably be found as high as one hundred and 

 twenty degrees Eahr. ; but there is reason to believe, that by the agency of an 

 efficient system of ventilation, this temperature may be so reduced, at least 

 during the cooler months of the year, as to allow of mining-operations without 

 unusual danger to health. 4. That for working mines of greater depth than 

 two thousand or two thousand five hundred feet, underground stages, with 

 independent winding machinery and engines, will be found not only to render 

 very deep mining practicable, but also to lessen the amount of risk from accident. 

 5. Lastly. Adopting a depth of four thousand feet as a limit to deep mining, 

 there is still a quantity of coal in store in England and Wales, sufficient to 

 afford a supply of sixty millions of tons for about a thousand years." 



In his summary of resources, Mr. Hull gives for England and Wales a total 

 coal-containing area of three thousand seven hundred and eleven square miles 

 which he considers may be worked to a depth of four thousand feet, giving thus 

 a. total available quantity of fifty-nine thousand one hundred and nine millions 

 of tons. Taking the present produce at sixty millions, and allowing three 

 millions for the increase of future years, he considers the above supply of coal 

 will last for a thousand years; and "that for many generations to come the 

 mineral resources of England arc capable of bearing any drain to which they 

 can possibly be subjected, either for home or foreign consumption." 



