﻿Bevieus—Prof. Ferd. Roemer's Lethcea Palceozoica. 31 



allow of our availing ourselves of mathematical analysis. But if 

 this be so, it is better frankly to acknowledge the fact, and not to 

 attempt to support or overthrow a theory by a show of numerical 

 accuracy, which has no sound basis to rest upon." This no doubt 

 will be a popular sentiment and a flattering unction to many to be 

 told, by one of Prof. Green's ability, that they who cannot calculate 

 are as well off as those who can. But surely Prof. Green will 

 acknowledge that in all such cases there are extreme limits, which 

 the quantities involved in any problem cannot exceed on one side, 

 or fall short of on the other, and thus the application of these to the 

 case in hand involves no " show of numerical accuracy," but is an 

 honest and a real way of deciding, within the possible limits, whether 

 a theory be true or false. 



Mr. CroU's theories of climatal changes are remarkably well 

 epitomized in the twelfth chapter, and are evidently favourably 

 entertained. Indeed this twelfth chapter strikes us as much more 

 satisfying than the previous one, which treats of the condition of 

 the earth's interior. The one subject has been almost as much con- 

 troverted as the other, although the latter is the older, and has 

 on that account had the advantage of being attacked by men of 

 the greatest power. Yet it is only lately that Geology has contri- 

 buted her share to the data of this great question, and very re- 

 cently indeed, if even yet, that physicists have learnt to perceive 

 that the facts of geology cannot bend to the results of physical 

 inquiry, but that, in order to form a true theory, neither can be 

 allowed to lord it over the other, and that the requirements of each 

 must be equally satisfied. 



A very noticeable and most valuable feature in Prof. Green's 

 work is the abundance of reference to original treatises and papers. 

 The book might be used as a nearly complete index to the whole 

 literature of that part of Geology of which it professes to treat. 



II. — Leth^a Palteozoica. By Professor Perd. Eoemer. Atlas of 



62 Plates. Large 8vo. (Stuttgart, 1876.) 

 niHIS Atlas of Plates is the first issued part of a "Lethcea geo- 

 _L gnostica," which, when complete, will cover the entire ground 

 of stratigraphical palseontology. The scheme is, on an enlarged and 

 improved scale, virtually a new edition of Bronn's well-known 

 work, with the great advantage of having the co-operation of several 

 specialists of authority in its production. The Palaeozoic portion 

 has been placed in the hands of Professor Ferdinand Eoemer, of 

 Breslau, whose life-long work among the fossils of the older rocks 

 has been successfully carried on in every part of Europe, and in the 

 New World as well as the Old. No choice could be more calculated 

 to arouse the highest expectations on the part of geologists and 

 palasontologists, and although we have yet before us only the illus- 

 trations of the text to come, still there is enough in the brief preface, 

 in the choice of fossils, and in the mode of their arrangement, to 

 show that the subject is handled by a veteran whose individuality 

 makes itself conspicuous even in such matters as these. 



