482 



NATURE 



\_Afarch 22, 



constant, 2.700,000 gallons by measure at 25 overproof 

 are removed each month from bond. Now, taking 

 the mean shade temperatures for the months from 

 November 1886 to April 1887, it appears that^ owing to 

 the contraction in these 2,700,000 gallons per month, 

 no less a quantity than 97,268 gallons of 25 over- 

 proof or of 121,586 gallons of proof spirit for the six 

 months would accrue in the estimation as now carried on, 

 and the duty on this amounts to ^61,000, now lost to the 

 Revenue. 



It is true that probably these shade temperatures do 

 not exactly represent the temperatures of the warehouse, 

 which will be more equable, but then the contents of a 

 warehouse if they lose their heat slowly also regain it 

 slowly, and the low temperature contracted during a long 

 and severe winter is perpetuated for a long period 

 throughout the year ; so that in all probabihty the 

 average temperature of the bonded spirit is below 51° not 

 only during six but during nine months of the year, and 

 assuming that the mean temperature did not exceed 

 47° during these extra three months, the additional loss to 

 the Revenue would amount to ^10,000. 



The foregoing statements have been published for some 

 time, and have not been confuted except in the usual 

 official Parliamentary style. This, we urge, is insufficient. 

 What the public wants to know, and has a right to learn, 

 is, what, if the Revenue authorities dispute these assertions, 

 are their grounds for so doing.-* Should this information 

 not be forthcoming, the opinion will gain ground that 

 another Government Department is trying hard " how not 

 to do it." 



PRESTwicH's ''geology:' 



Geology : Chemical, Physical, and Stratigraphical. By 

 Joseph Prestwich, M.A., F.R.S., F.G.S., Correspondent 

 of the Institute of France, Professor of Geology in the 

 University of Oxford. In Two Volumes. Vol. II. 

 Stratigraphical and Physical. (Oxford : Clarendon 

 Press, 1888.) 



IT is just two years ago that we were called upon to 

 notice the first volume of this important treatise ; and 

 the author of it has now signalized the completion of his 

 labours at Oxford by giving to the world the second and 

 concluding volume of the work. Its publication has long 

 been eagerly looked forward to, and now that the book is 

 before us, we may safely assert that it more than justifies the 

 high expectations which have been formed concerning it ; 

 and we confidently predict that it will add to the already 

 high reputation of the veteran geologist to whom we are 

 indebted for it. 



In reading the first chapter of the book, everyone must 

 be struck by the fact that a distinct advance has been made 

 in the mode of treatment of the great problems of strati- 

 graphical geology. Speaking of the " order of succession " 

 and "the breaks in continuity" in the series of stratified 

 rocks, Prof. Prestwich writes : — 



"The great time-divisions are of almost universal 

 application ; but the smaller 'breaks in continuity,' which 

 are of frequent occurrence in all areas, are subject to 

 constant differences of extent and value ; consequently, in 

 filling up the details of the several geographical areas, each 

 one is found to have its own local stamp, and possesses its 



own special terms, some knowledge of which is as essen- 

 tial to the geologist as is the language of a country to the 

 traveller, if he would pass through it with profit." 



The author then proceeds to show how impossible is 

 any universal scheme of geological classification, and to 

 discuss the question, first raised by Edward Forbes and 

 Prof. Huxley, as to how far geological equivalence is to 

 be regarded as being identical with actual synchronism. 



He insists that, in distant areas, strata cannot be corre- 

 lated by identical species, but only by the presence of the 

 same characteristic genera, and he fully admits the effects 

 of migration of forms of life from one region to another 

 in causing strata of different ages to present very similar 

 faunas or floras. Such considerations as these, the author 

 argues, must always prevent us from regarding the series 

 of formations as being strictly contemporaneous in distant 

 areas, or the breaks between them as being universal 

 ones. 



Prof. Prestwich points out some of the difficulties con- 

 fronting geologists, in the following suggestive passage :— 



" In Western North America the great break so con- 

 spicuous between the Cretaceous and Tertiary series does 

 not exist, and there arc passage beds having characters of 

 the two periods in common. In a similar way the Car- 

 boniferous strata in America pass gradually into the 

 Permian, without the unconformity which exists here. In 

 India the Gondwana system forms a consecutive series 

 from the base of the Permian to the top of the Jurassic 

 strata. In New Zealand, again, no marked line can be 

 drawn between the Cretaceous and Tertiary series, the 

 Upper Cretaceous and Lower Eocene forming unbroken 

 and continuous series." 



He then proceeds to give not one table of classification 

 for the sedimentary rocks, but six different ones, adapted 

 respectively to Europe, India, North America, Australia, 

 New Zealand, and South Africa. And having thus at the 

 veiy outset shown what are the obstacles in the way ot 

 the exact correlation of distant deposits, and established a 

 philosophical basis of classification for strata, he takes up 

 the consideration in succession of the several great geo- 

 logical systems ; he selects the method of beginning with 

 the oldest, and passing upwards in the scale, candidly 

 admitting, however, that the opposite plan is not without 

 its merits and advantages. 



The account given in successive chapters of the several 

 formations, their typical development in this country, the 

 groups of fossils by which they are distinguished, and their 

 chief foreign representatives, is eminently clear and readable- 

 This merit is the more conspicuous from the circumstance 

 that the mass of detailed information to be selected from 

 and arranged in writing a work on stratigraphical geology 

 is so enormous and bewildering, that such works are very apt 

 to suffer in their style, and to become heavy and encyclo- 

 paedic in character. But Prof Prestwich has admirably 

 avoided this danger. 



The author does not waste any time in discussing barren 

 questions of nomenclature. In the case of the three 

 systems of the older Palaeozoic, he follows the common 

 custom of calling the oldest " Cambrian," the second 

 "Lower Silurian," and the third "Upper Silurian"; though 

 pointing out in a footnote the significance of the term 

 " Ordovician." 



Very striking features in the book are the chapters in 

 which are summed up the characteristics of the faunas- 



