October 27, 1923] 



NA TURE 



615 



that it contains no reference to such important branches 

 of geophysics as terrestrial magnetism, earth currents, 

 aurorse, and atmospheric electri( ity, not to say meteor- 

 ology. Within its chosen limits^ ho\vi'\er^ it affords a 

 welcome summary of a considerable body of knowUd-c 

 concerning the earth, which has not hitherto been 

 accessible '\\\ anylliing like so concise and handy a form.. 

 The Work is divided into three parts. In ditferent 

 authors, but is as unitary a treatise as c an he expected 

 in the case of a wide field of rather loo>el\-eunnected 

 studies such as geophysics. The first part occupies 

 more than half the volume, and is distinguished from 

 the two later parts by its lar.:ely inatheinatieal char- 

 acter ; it deals with the figure of the eartli. tlie thmrv 

 of tides and seiehe>. and tlie density and ri,uidit\ oi the 

 earth. The determination ol the geoid 1)_\" triangula- 

 tion is first hrieth' exphdned. including an account of 

 the es.^ential features of the instruments used and the 

 methods of reduction. Tiie application of gra\ity 

 measurements to the same problem is then dealt with ; 

 a short summary of pottntial-theory is followed l)y a 

 description of the instruments and method-, u^cd in 

 gravitv-determinations, both absolute and relative : 

 Clairaut's theorem conncctinu the ellipticitx' of the 

 earth with the ratio of -ra\it\ at pole and e(iuator and 

 of gra\it\- with '■ ' i h>rcf at the equator is 



proN'ed anrl rli-i n '!c\!"n with ohscrx ;it idus 



for the n- ' n.iratcl) . ■Jlici'f 



1 ' i 1.1 j)i ( I i II I liir,^--i ;i rim n I ol hrluht • ' ■ ■ 



!i\- Ifv-rlliTv:. t ri'joiioTiii-tricai ,-.uiac\ i: 

 |);tro' ' ! 1 >\' a lon-rr hut con- 



dcn^ u ■ .,11,1, '■ '' ■■ ■ ' ■■' the M-a 



itvi-li : the I! Monii is 



( '. following l)ar\\iii in the iiiam tnoi i \ m a 



;,,,,, ,>:;icnci' i- mill,- til iKr important uoi'k li\ 



licld ). and t he 1 1 |nih 



I'roudinan ai 

 brium th(oi\ 



.■;inal tin m 



;aiiiical 1 i 1! .\n"\'> 



Miip.ariMd uri'cnts 



d iiM : the iTnport.int in- 



fluciic( 

 cient ni 



V 



dc!l 



and 



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^\\A It ut !i 'ii. nit-an 



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deals in a non-mathematical, discursiA^e way with the 

 borderland region between geodesy and geophysics. 

 There the causes which have led to the present surface 

 features of the earth are discussed. Without accepting 

 Wegener's theory of continental dis])la( ements. the 

 author adopts the broad principle that large lateral 

 displacements of continental blocks must be taken into 

 account in geology, though discounting the \-ery un- 

 certain astronomical evidence thus far adduced in 

 fa\our of measurable rates of variation of relative 

 longitude. Considerable space is also devoted to the 

 causes of vulcanism and of earthquakes. 



Our Bookshelf. 



Civil Engineering Geology. By Cyril S. Fox. Pp. 

 \vi + i44. (London: Crosby Lockwood and Son, 

 1923.) 185. net. 



A nviL engineer laid the foundations of modern 

 geolog\- : it i.> tlnrifore singularlv inapjiropriate that 

 civil engineers should W sonu'wiiat dependent upon 

 the geologist tor dciiMxe opinions on the L:cological 

 aspects of en-incering schemes, 'hhe author would 

 attribute the eiiLiineer's diffidem i' in the matter of 

 geolog\- to the air of specialisation witli wliich an 

 awesome nomenclature has iinoted the suliject. 

 l-'.n^iiieers are themst'Ki'S rather at fault in ha\ ing 

 allowed till- cloak ot William Smiih to deseend on 

 otli(i'>' shoulders. I :il operations 



in\o|\cs little \\v •'■■ ■ - ..-e application 



ol 111': t prmi 1] lie- ■ ■! iMr\ atioiis made 



on the enuineer > own lj ; i hcki. 



(ieoloL;\' is now. however, a subject studied \>\ most 

 em^ineering students, who are well ei]uip.p((l loi" the 

 stndw 'I'he author's purjjose is to indui t i i\ il eiii^uuers 

 to a territoiA which the\' miLiht ha\"i' shand eqiialh' 

 Willi -eolouists iVom the lir>t. and tiiis purpose is 

 achieved in an iuspirini; book : it deals in a thoroiiuhlv 

 prai til al wa\" with gcoki^ix' h^om the enL!ineer's point of 

 \ iew . and is in no m use a slender onuinal desi-n ere( ted 

 oil a trimmed mass ol material i|ua!ried iioiu otiier 

 \sorks the antiiiii's pnlihshed woik ( \((j>te(i. A 

 bi'iel introduction leads (hrectb to the pi'obleins n] 

 watei" siippb ( I't . 1.1 : I't . 1 I . deals with lie Id operations . 

 I't . III. with build in;..; matci lals. I'rom iirst paLe tn ktst 

 the liodk liears the si, imp ol ( \periciice and praiiii.d 

 ai qii.iintance wit! is' problems, lllustr.itions 



iiK hide sket( lies : ai the author's tield iiote- 



■ " alv --skc'li ■ " ' ' -s a 



hlel, t!., v/l\\ 



•u\v 

 ted 



h\ iiumerMU and pliotoL;iapii^. 



\ iivac: ; iiliar w ith : enli-v , the 



methods Ml iiprcsenti 



■ 1 i !(! 1 1 I I r. I I .1 1 1 \ 1 i il 1 1 ' 



' \ in 



i. 11.11 link 



I 111 .luthor 

 hi' h w ill 



i\ ' ; . .; I J I 



