no 



SCIENCE. 



[Vol. vol., No. 182 



yet published, will include chapters on stratig- 

 raphy and paleontology, and a discussion of 

 theoretical questions connected with historical 

 geology and the evolutions of the earth. This 

 will therefore probably be the more entertaining 

 of the two ; but the book now before us is attrac- 

 tively written and makes easier reading than most 

 geological manuals. Its style is between the ex- 

 treme condensation of the encyclopedic text-books, 

 and the more literary form of Lyell's ' Principles.' 

 Except in the chapters that are necessarily occu- 

 pied with simple definition and tabulation, there 

 is a satisfactory amount of argument and discus- 

 sion, and a careful presentation of both sides of a 

 question ; so that the learner's attention is held to 

 the facts long enough to allow him to acquire 

 them familiarly, and to perceive that their proper 

 understanding requires a higher mental process 

 than mere memorizing. The work is further 

 intentionally a statement of the evolutionary 

 rather than of the uniformitarian view of geology, 

 which Lyell's leadership so long in England placed 

 too prominently before many students : there was 

 under Lyell's teaching no room between uniformi- 

 tarianism and catastrophism for the safer middle 

 ground which Prestwich clearly states, and which 

 is now certainly the dominant view held by work- 

 ing geologists. The change in the rate of denud- 

 ing processes and of eruptive action from ancient 

 to later geological times may be named in illustra- 

 tion of this. Under the latter subject, it is an 

 additional satisfaction to see prominence given to 

 the mechanical origin of eruptions, and only a sub- 

 ordinate importance attached to Scrope's theory of 

 the action of steam and other gases ; and to find 

 definite statement of the metamorphism of erup- 

 tive as well as of sedimentary rocks. Indeed, it 

 would be easy to name many more examples of 

 treatment that must commend themselves to the 

 American as well as to the English taste, while 

 there are only two sections that are likely to excite 

 any general dissent, — one on the origin of valleys, 

 which attributes too much influence to fissures to 

 find full acceptance, at least in this country ; and 

 another in which much importance is attached to 

 Elie de Beaumont's extinct theory of parallel 

 mountain-ranges, which is certainly given more 

 space than students in this last quarter of the 

 century should ask for it. The author's familiar- 

 ity with the geology of this country has not been 

 such as to prompt many quotations from our sur- 

 veys, nor to change the triassic coloring of the 

 copper-bearing rocks of Lake Superior on the 

 reduced copy of Marcou's geological map of the 

 world, which serves as a frontispiece ; so that, as a 

 book for class reference in our higher schools and 

 colleges, this work will hardly gain the reputation 



of Geikie's text-book : but, if the excellent 

 fashion of placing different books in the hands of 

 every member of a class could be introduced, this 

 one would certainly be one of the most popular. 



W. M. D. 



PORTERS MECHANICS AND FAITH. 



This work is one of those attempts, so common 

 in our day, to ' reconcile science and religion.' 

 The main thesis of the author, which he endeavors 

 through many chapters to prove, is this ; that all 

 truth, physical and spiritual, is made known to us 

 by 'revelation.' and could never become known 

 to us by any other means. Thus, he says that in 

 mechanical science, " man, in his conscious igno- 

 rance, and with a sense of entire dependence, 

 makes his appeal immediately to the Infinite 

 Source of truth ; that the methods of experiment 

 and observation are the divinely appointed way in 

 which this appeal is made and the revelation of 

 physical truth is received " (p. 32). Having estab- 

 lished this thesis, to his own satisfaction, he goes 

 on to infer, that, since all other truth is given by 

 revelation, we should naturally expect that re- 

 ligious truth, the most important of all, would be 

 given in the same way. Thus he thinks to estab- 

 lish the doctrine of revelation in the theological 

 sense. 



Now, in all this there is great confusion of 

 thought, resulting from the use of the word ' rev- 

 elation ' in two quite different senses. The ' rev- 

 elation ' which the author speaks of in physical 

 science is nothing but the presentation of objects 

 to our senses, and this is not a revelation of truth 

 at all. Truth is not a property of objects, but of 

 thoughts ; and all our thoughts, whether true or 

 false, are the product of our own mental activity. 

 It is absurd, therefore, to say that scientific truth 

 is revealed to us from an external source. On the 

 other hand, the sacred books of rehgion are held 

 to contain religious truth itself in the form of 

 propositions, and we have nothing to do but to 

 receive and assimilate it. At best, therefore, 

 there is nothing more than a poetic analogy be- 

 tween the two cases, and nothing whatever to 

 base an argument on. 



Mr. Porter's main doctrine being thus defec- 

 tive, it is unnecessary to criticise his book in detail ; 

 but we would call attention to the chapter on 

 ' The revelation of God,' as an example of the 

 author's method. He expressly says that God can- 

 not be known by the intellect, but only by love — 

 with much more to the same effect. It is not by 

 such methods as these that science and religion 

 can be harmonized. 



Mechanics and faith: a study of spiritiial truth in 

 nature. By Charles Talbot Porter. New York, Put- 

 nam, 1886. 12*. 



