IV 



NA TURE 



rSnppleiiieut, 

 January i8, i8g 



are destructive, some protective or constructive. Peat 

 and coal are considered, so also Foraminifera, Radiol- 

 aria, and Corals. Part iii. is headed "Changes from 

 Within," and the old Temple of Serapis comes before us 

 as a witness to the fluctuations of level. Movements in 

 the earth's crust, faults, flexures and overthru-ts, and the 

 formation of mountains are considered. We pass on to 

 volcanic action and earthquakes, and eventually to the 

 subjects of joints, spheroidal structures, nodules, and 

 mineral veins, all of which are briefly noticed. 



In Part iv. we come to to what some may consider as 

 geology proper ; or, " The Story of Past Ages." Natur- 

 ally we most of us like to go back to the very beginning, 

 and glean what knowledge we can of the earth's probable 

 origin ; and the author briefly reviews the evidence. 

 More interesting, however, is the chapter which deals with 

 the eras and subdivisions in geological history, and we 

 feel at any rate on terrajirma. In regard to questions of 

 correlation, the views of Prof Huxley on " homotaxis " 

 are given more prominence than some students of "zones" 

 will admit to be justified by the present state of our 

 knowledge. Nevertheless, it must be admitted that the 

 philosophy of zones has yet to be understood, and, as the 

 author urges, "geological contemporaneity from the 

 general similarity of fossils must not be pressed too far." 

 Each area must be interpreted as far as possible by its 

 own evidence, and when the sequence of organic remains 

 is found to be alike in areas widely apart, even the 

 highest authorities do not claim precise, but only 

 approximate, contemporaneity. 



The Archaean era is one to which the author has paid 

 much attention It is a complex and comprehensive 

 group, and barren of life, so far as our present knowledge 

 go;s. Many crystalline schists and gneisses are pro- 

 visionally referred to this division, and the author is 

 inclined to regard their general characters as a v.itnessto 

 their age. He points out how evidence to the con- 

 trary has in several cases broken down. Still, an attitude 

 of reserve is desirable, when we bear in mind that great 

 earth-movements have taken place in Tertiary times, and 

 thatdeep-seateJ metamorphism, as Mr. Barrow has shown 

 in the south-eastern Highlands of Scotland, is all that is 

 wanted to produce the results. 



From the chaos of the Archaean era we pass on to a 

 chapter dealing with "The Bailding of the British 

 Islands," and we are furnished with a brief account of 

 the Cambrian, Ordovician, and Silurian periods. Re- 

 storations of the possible geography of Britain in early 

 Carboniferous and subsequent times are given, after 

 Jukes-Browne, and we are led on stage by stage with 

 brief descriptions through the series of formations. 

 With regard to the origin of boulder clay, the agency of 

 coast-ice is maintained in opposition to that of ice-sheets ; 

 but in this, as in other cases, where serious alternative 

 opinions are held, the different views are stated. 



" The Building of Europe and other Continents" is the 

 next subject provided for us, and we are given a brief 

 sketch of the history of the Alps. Then follows "A 

 Sketch of the Earth's Life History," which might better 

 have been incorporated with the accounts of the several 

 formations whose history was previously told, for the 

 leading types of life are treated stratigraphically. Here, 

 in some respects, the popular meanings given to the names 

 NO. 1264, VOL. 49] 



of fossils are more amusing than useful. Thus we have 

 the Microlestes or ''little thief," the Droinaiheriuin or 

 " running beast," the Turritella or " cockspur," the Ple- 

 siosaiiriis or " neighbour-lizard," the Pliosaiirus "more 

 nearly a lizard," and so on. 



The concluding part is " On Some Theoretical Ques- 

 tions." It de lis with the age of the earth, which " is long 

 but it is very far from being boundless." The author, in 

 fact, as stated in his preface, thinks ihat we can discover 

 " by processes strictly inductive, some sign of its begin- 

 ning and some foreshadowing of its end." We are not 

 disposed to challenge the statement. 



The permanence of ocean basins and of land areas is a 

 well-worn theme, on which " agreement ceases" ; but the 

 author is far from dogmatic on the subject. The prob- 

 lems of climatal change and of the distribution of life on 

 the earth, form the topics discussed in the closing 

 chapters. 



The general reader who peruses this volume cannot but 

 gain a sound general knowledge of geological science. In 

 the ordinary sense of the term we cannot call it a very 

 " popular " book, for it contains too much solid reading to 

 please those who would read for entertainment. It 

 must be read by those desirous of instruction ; by them 

 it will be appreciated, and for them we believe the work 

 has been written. To the more serious student it will be 

 of service in regard to Prof. Bonney's views ; but as a 

 work of reference it lacks importance, from the fact that 

 the author does not, as a rule, cite original authorities, 

 but gives references mainly to text-books and other works 

 of a general character. That he has laboured with en- 

 thusiasm, and lightened his labours w ith many a pleasant, 

 and sometimes a pungent, remark on things in general, 

 will be evident to all who take up this volume. 



CAYLEY'S PAPERS. 



Ihe Collected Mathematical Papers of Arthur Cay ley, 

 Sc.D., E.R S., Sadlerian Professor of Pure Mathe- 

 matics in the University of Cambridge. (Cambridge : 

 University Press, 1889, et seq.) 



LATE in the year 1887 the Syndics of the University 

 Press requested Prof. Cayley to allow his mathe- 

 matical papers to be reprinted in a collected form. To 

 this he acceded, and also undertook the work of super- 

 intending the impression and of adding such notes and 

 references as appeared to him desirable. 



Cayley's papers, commencing in the year 1841, have 

 appeared in every periodical mathematical publication 

 of importance in Europe and America. A worker in 

 pure mathematics, in whatever special department of 

 geometry or analysis, is well-nigh certain to find that his 

 subject has come under Cayley's hand, so comprehensive 

 are the researches that he has presented to the scientific 

 world. A study of one or more of these papers being 

 thus inevitable, it is easy to appreciate the importance 

 to a student of this wonderful collection — wonderful alike 

 in regard to extent, to variety, and to quality. It is not 

 our intention to attempt a sufficient review of the six 

 volumes that have appeared in the five years that have 

 elapsed since January, 1889. If this were the end in 

 view, a volume would be necessary. On this occasion 

 we purpose to glance rapidly at some of the great dis- 



