482 



NATURE 



{_Scpf. 



1880 



against the classification of the bottom beds at Kentish 

 Town and Crossness with the Old Red Sandstone, which 

 seems to have escaped notice. Having the series unmis- 

 takably present in the Devonian type at Cheshunt and at 

 Meux's, it would be strange indeed were it to occur in its 

 wholly distinct Old Red Type at Kentish Town, between 

 those two places, and at Crossness, not very many miles 

 from the latter of them ! I believe that no such thing is 

 known to occur anywhere ; the two types of what is gene- 

 rally taken to be one great geological system being limited 

 to separate districts, and not occurring together." 



There is one other point upon which Mr. Whitaker's 

 views as expressed in the work before us are well worthy 

 of the attentive consideration of geologists. On p. 20 he 

 remarks : — 



"It has been said that although, from the cores brought 

 up from some of the deep borings, we can estimate the 

 angle of dip of the rocks, yet for calculations as to the 

 probable extent of any of these rocks, and as to where 

 other rocks may bo expected either to come on above or 

 to rise up from beneath them, it is needful to be able 

 also to approximate to the dircclioii of dip. I am led to 

 think, however, that this is really of less importance than 

 at first sight seeins to be the case ; for judging by what 

 we generally see of the older rocks in districts where they 

 are at the surface, they are much subject to disturbances 

 and are thrown into great rolls or folds, so that whilst at 

 one spot dipping north, near by they may turn over and 

 dip south. We find, too, in the coal-fields of Belgium 

 and of the north of France frequent evidence of sharp 

 folding, and indeed of inversion of these older rocks 

 underneath the even and almost undisturbed Cretaceous 

 and Tertiary beds. I think therefore that were we able 

 to find the direction of the dip of the rocks in any of our 

 deep wells it would be unsafe to argue from that alone as 

 to the probable succession of the beds in any direction 

 for a considerable distance." 



Mr. Whitaker's suggestions as to the direction in which 

 it might possibly be of use to search for the Coal measures 

 in the south-east of England are offered with a cautious 

 reservation which is highly to be commended ; it is 

 evident, however, that he agrees with Mr. Godwin-Austen 

 and Prof. Prestwich in the opinion that the southern 

 suburbs of London and the line of the North Downs 

 afford the most promising fields for future research. It is 

 greatly to be regretted that no attempt has been made to 

 obtain the necessary means, either from public funds or by 

 private subscription, for carrying out this most interesting 

 experiment. 



It is not only in connection with his account of the 

 great underground ridge of pateozoic rocks that Mr. 

 Whitaker has been able to make valuable additions to this 

 work. His account of the chalk and the boulder clay 

 have been supplemented by some remarks giving the 

 reader an idea of the latest views which have been pub- 

 lished concerning the mode of origin of those formations. 

 To students of Tertiary geology Mr. Whitaker's remarks 

 on the pebble-gravel round London will prove interesting, 

 while archaeologists will find a valuable record of the 

 discovery of a canoe (now placed in the British Museum) 

 in the peat cut through in the works of the Victoria-Docks 

 Extension. 



This admirable guide to the geology of London is 

 published at the low price of one shilling, and the demand 

 which has already produced the exhaustion of two editions 

 ought surely to convince the authorities of the Geological 

 Survey that it would be wise of them so to curtail the 



expenses of publication in the memoirs which they issue, 

 as to permit of their being sold at equally reasonable 

 rates. 



PROF. A. GRAY'S BOTANICAL TEXT- BOOK 

 Th,- Botanical Text-Book (Sixth Edition). Part I.— 

 Stnicliiral Botany, or Organography on the Basis of 

 Morphology, to which is added the Principles of Tax- 

 onomy and Pliytography, and a Glossary of Bota?iical 

 Terms. By Asa Gray, LL.D., &c., Fisher Professor 

 of Natural History (Botany) in Harvard University. 

 (New York and Chicago : Ivison, Blakeman, Tayler, 

 and Co., 1S79. London : Macmillan and Co.) 

 n^'HE near prospect of a visit from one who has for 

 -L upwards of a quarter of a century held the undis- 

 puted position of the first botanist in the New World, 

 both as a teacher and a writer, reininds us that his last 

 and in some respects the most important of his many 

 valuable publications, the " Botanical Text-Book," has 

 not yet been noticed in this journal. 



Prof. Asa Gray is the author of various elementary 

 works upon the science he has so long cultivated and 

 taught, some adapted for the old and some for the young, 

 unequal in every respect except that of merit and ad- 

 mirable adaptation to their several purposes. Such are 

 his "First Lessons in Botany," which contain just so 

 much as is necessary to obtain such a knowledge of the 

 botany of flowering plants as will enable a student to 

 ascertain their names and affinities by the use of the 

 ordinary descriptive manuals ; his " How Plants Grow : 

 a Simple Introduction to Structural Botany," which is 

 the most lucidly written work of the kind known to us ; 

 his " Lessons in Botany and Vegetable Physiology ;" his 

 " Manual of the Botany of the Northern United States ;" 

 and, above all, his " How Plants Behave : an Introduc- 

 tion to a Study of the Habits and Movements of .Plants, 

 adapted for the Young," which is a marvel of good 

 arrangement and clear expression, whilst the subject is 

 rendered in the highest degree attractive to both old and 

 young. 



These and other elementary works on botany are, 

 though sold by thousands in the United States, com- 

 paratively little known on this side of the Atlantic. The 

 same cannot be said of a more comprehensive work by 

 the same author, written for more advanced students, 

 and as a book of reference for the working botanist, 

 namely that which heads this article. The " Botanical 

 Text-Book" appeared so long ago (as a first edition) as 

 1842, and immediately took rank as a first-class educa- 

 tional work in all English-speaking countries, and from 

 that time to the present, during which the five editions 

 which have appeared, being always brought up to date in 

 point of matter, have been successively recognised by 

 professors in British universities as the best introduction 

 to botany extant in the language, and recommended 

 by many to their pupils as the one they should use. 



In all the five editions all the branches of botany have 

 been treated of under the heads of Structure, Physiology, 

 and System ; but the twenty-three years that have elapsed 

 since the appearance of the last edition have so greatly 

 enlarged our knowledge of the physiology of vegetables, 

 and of the vast assemblage of plants known as crypto- 



