RevieiDS — A. Strahan — Coals of South Wales. 519 



show it later than the lower," and a third that " the loss of 

 bituminous matter takes place at a more rapid rate in a south to 

 north direction than in an east to west direction." 



A very complete and carefully carried out series of analyses have 

 been made of coal methodically collected for that purpose, the results 

 of which, with details of the methods employed, occupy a large part 

 of the memoir. 



Chapter ii, on the sequence of the seams, is short and unsatisfying. 

 No reasons are given for the individual correlation of seams, and 

 palseontologieal methods might have been unknown. The idea of an 

 appeal to fossils, either plants or shells, does not seem to have occurred 

 to the author, although in other coalfields excellent results have been 

 obtained. 



Chapters iii-viii deal with statistics and the explanation of the 

 plates, and the memoir closes with a chapter on the " Origin of 

 Anthracite." Here previous views are discussed, and the theory is 

 adopted that "the differences between anthracitic and bituminous 

 coals of South "Wales are mainly due to original differences in 

 deposition," for the following reasons: — 



1. The seams are not all similarly anthracitic; though each seam 

 is generally more anthracitic than the one above it, there are many 

 exceptions to this rule. 



2. The anthracitic character was not due to faults, but existed 

 before the faults were formed. 



3. The anthracite existed as such before the coalfield was reduced 

 by denudation to its present dimensions. 



4. The percentage of ash diminishes pari passu with the decrease 

 of bituminous matter. 



It must be confessed that the conclusion leaves the question in an 

 unsatisfactory condition, and no details of what may have been the 

 difference in deposition are suggested ; therefore the vera causa of 

 anthracitization is still to be discovered. The question in the present 

 volume has been attacked only from the chemical side, and it would 

 be interesting to know whether the microscope would have revealed 

 any structural or biological changes in the seams of coal. A good and 

 adequate index completes the volume. 



W. H. 



II. — The Rhodesian Miner's Handbook. By P. P. Mennell, F.G.S. 

 pp. X + 143. Bulawayo : Ellis Allen, 1908. Price 5s. 



rPHIS valuable handbook forms publication No. 4 issued by the 

 1 Rhodesia Museum, of which institution the author has been for 

 the past six years the curator. Of its extreme usefulness to the 

 prospector in Rhodesia there can be no question, and he will save 

 himself much waste of time, and possibly bitter disappointment, if 

 he takes care to include it in his outfit. The book teems with 

 invaluable information relating to the ores of commercial importance, 

 the type of rock in which they may most probably be found, the 

 identification of the principal mineral species, the testing of the 

 quality of a lode, the steps to be taken to establish a title to a mine, 



