June i8, 1891] 



NATURE 



149 



scribe briefly some of the principal engineering works 

 carried out, at home and abroad, within the last fifty 

 years. The book is well printed, and the illustrations 

 are excellent, although there might perhaps have been 

 more of them, considering that the general reader has to 

 be provided for. N. J. L. 



GEOLOGICAL EXCURSIONS. 



Geologists^ Association : a Record of Excursions made 

 between i860 and 1890. Edited by Thomas Vincent 

 Holmes, F.G.S., and C. Davies Sherborn, F.G.S. 

 (London: E. Stanford, 1891.) 



THE Geologists' Association began its useful career of 

 work more than thirty years since. It has stimu- 

 lated — more, perhaps, than any other body— a real in- 

 terest in geology among those who live in and about 

 London, because it has enabled students, still near the 

 outset of their work, not only to meet for mutual help 

 and encouragement, but also to be aided by those of 

 repute in science. Of its meetings, not the least pleasant 

 and useful are the e-xcursions. At first these were made 

 generally once a week, so long as weather permitted, and 

 they occupied a Saturday afternoon or at most a single 

 day. Then an occasional journey of longer duration was 

 attempted ; now it is usual to undertake excursions, last- 

 ing two or three days, at Easter and Whitsuntide, and 

 one of a week or more during the summer holidays. 

 Before each excursion a flysheet is issued to the members 

 with a brief description of the geology of the locality, 

 illustrated by diagrams and containing references to 

 books and papers. Afterwards, a report of the excursion 

 is inserted in the Proceedings of the Association. It was 

 a happy thought to collect together in one volume these 

 scattered notices, for they give succinct descriptions of 

 almost all the localities of geological interest readily 

 reached from London, so grouped as to be conveniently 

 accessible. Thus the student, instead of having to com- 

 pile for himself, from books or maps, a plan of campaign, 

 whether for an afternoon or for a longer time, finds every- 

 thing arranged ready to his hand, and is directed to the 

 sections best worth visiting. These diagrams and reports 

 possess a further value, that they frequently record sections 

 which can be no longer examined, because they now either 

 are overgrown by vegetation, or have been removed in 

 quarrying. The work therefore is a geological guide-book 

 of an exceptional and a very convenient character to a 

 large district around London, and to several other locali- 

 ties of special interest in England. 



The plan which has been followed in compiling the 

 volume is stated in the preface. The excursions are 

 grouped, as far as possible, within county boundaries; 

 where more than one visit has been paid to any place, 

 the editors have "either suppressed the shorter, and 

 retained the fuller, or given from each account that 

 which is not to be found elsewhere." The reports have 

 been condensed by the excision of matters of general or 

 merely temporary interest, and although references are 

 made to all excursions up to the year 1890, no reports are 

 given of later dates than 1884, because since 1885 it has 

 been customary to print all these in the November number 

 of the Proceedings, so that they can be easily consulted- 

 NO. I 1 29, VOL. 44] 



The thanks of the Association— indeed of a wider circle 

 of geologists— are due to the editors for the pains which they 

 have taken in discharging a very laborious duty. It seems 

 almost ungracious to criticize, and to do it effectively 

 would require encyclopaedic knowledge ; but we think that, 

 though it may have been " impossible to send each report 

 to the original reporter for revision," it would have been 

 prudent to submit it to someone with a special know- 

 ledge of each district. These reports occasionally con- 

 tain obiter dicta, or the crude speculations of members 

 who are better acquainted with their own locality than with 

 the principles of the science. Hence obsolete notions are 

 preserved like flies in amber : these may perplex, but they 

 cannot help the beginner. By way of testing the results 

 of the editors' method, we have examined the reports of 

 two or three districts with which we are specially familiar. 

 The statement on p. 203 about the section at Roswell 

 Pit, near Ely, is misleading. The natural interpretation 

 of its words would be that the Kimeridge clay formed a 

 part of the great erratic. This, in reality, consists of 

 Cretaceous rocks, the Jurassic clay being in situ. On p. 

 216, the sentence " at the base, as at the top of the Gault," 

 should have been " below the base, as above the top." 

 Again, the clay beneath the neighbouring Upware Hme- 

 stone, now admitted to be Coral rag, cannot well be 

 Ampthill clay, and we are not aware of any evidence in 

 favour of this view. Again, the account of Charnwood 

 Forest needs correction. At p. 463 a statement is quoted, 

 which was published without due authority, and has been 

 recalled by the author. On pp. 465 and 466 the sugges- 

 tion that the Charnwood Forest rocks " ought to be called 

 Laurentian" should have been cancelled. It was ground- 

 less, even as Laurentian was defined in 1875 '• it is absurd 

 now. All reference to the " Archaean Petrology " of Prof. 

 Ansted might well have been omitted. On p. 472, Peldar 

 Tor is twice misprinted Peddar Tor. We know of no 

 ground for the statement, on p. 473, that " the quartz [in 

 the rocks of this neighbourhood] appears to be of sub- 

 sequent formation." Doubtless similar defects could be 

 pointed out by others ; indeed, our own list is not quite 

 exhausted, but we have no desire to carp at a book on 

 which so much labour has been bestowed, and prefer to 

 welcome it as a valuable addition to British geology, 

 which will be indispensable to all students who live in 

 the neighbourhood of the metropolis. T. G. B. 



OUR BOOK SHELF. 



Across East African Glaciers : An Account of the First 

 Ascent of Kilimanjaro. By Dr. Hans Meyer. Trans- 

 lated from the German by E. H. S. Calder. (London : 

 George Philip and Son, 1891.) 



Long before he thought of exploring any part of Africa, 

 Dr. Meyer was an experienced and enthusiastic traveller. 

 The idea of undertaking explorations in " the Dark Con- 

 tinent" was suggested to him by the fact that while the 

 German colonial possessions in the west of Africa had 

 been thoroughly investigated under Government super- 

 vision, and at the Government expense, those in the 

 East had been left to the more limited resources of 

 commercial companies. It occurred to Dr. Meyer that 

 he might do good service to his countrymen by devoting 

 himself to the task which the German Government seemed 

 so unwilling to undertake. Accordingly, in 1886, he began 

 to make preparations for the accomplishment of his plan 



