448 



NATURE 



\Sept. 2 1, 1876 



tree-lifter and of its advantages in transplanting large 

 trees. The principle of transplanting trees with a large 

 ball of earth attached to the roots is, however, so well 

 known, and tree-lifters of similar construction to that here 

 described are now so generally used, that we follow the 

 example of the author in his brevity, and simply dismiss 

 this part of the subject which he calls the " practical part 

 of transplanting," and turn to Part 2, which is devoted to 

 the " theory of transplanting, or physiology of trees in 

 reference to transplanting." It is apparently for the pur- 

 pose of recapitulating and condensing the views of various 

 authors of acknowledged reputation in the several branches 

 of vegetable physiology, and of expressing his own 

 opinions thereon, that the author has put this book to- 

 gether, all that is really directly connected with the title 

 being contained, as we have before said, in the first eleven 

 pages. The author, however, at the beginning of Part 2, 

 candidly says : " Before entering on physiology, I would 

 say one word to defend myself from the charge of egotism 

 and plagiarism. When I mention Sir Humphry Davy, I 

 may say that immortal names are among those who have 

 written on the physiology of trees ; yet so much doubt 

 and difference prevail among the authors on the subject, 

 that one cannot adopt a single opinion without opposing 

 many, held by minds, perhaps, as clear and comprehen- 

 sive as Sir Humphry's. It is, then, to save the reader's 

 time if I lay down as certain what men have doubted or 

 controverted, or if I use the words, ' I think this,' or ' 1 

 think that,' in stating other people's opinion." 



Space will not permit us to follow the author through 

 all his reasonings \ it will suffice to mention that no 

 less than forty- one pages are given to the considera- 

 tion of the subject of the course of the sap, in which the 

 author tilts at several well-known English and Conti- 

 nental botanists whose theories are adverse to his own. 

 Lindley is the most recent authority quoted in the 

 original edition, and the opinions of later writers have 

 not been embodied in subsequent issues. What we 

 have already said will show the character of the book. 

 The style of writing may be gathered from the first 

 paragraph in the chapter on the course of the sap, 

 where the author says : " However much we may dispute 

 on how the sap gets into the tree, we shall all agree that 

 it does get in somehow ; and but for Dr. Lindley, I believe 

 we should all agree on the course which it then takes." 

 Further on, in connection with the theories of the con- 

 traction and expansion of the wood, caused by alternating 

 heat and cold, and of the pumping action from the mo- 

 tion caused by wind, Col. Greenwood writes : " Look into 

 the hot-house and the hot-bed. In these neither of these 

 causes exists. Not a breath of wind enters ; nor is 

 any alternation of heat and cold allowed. Yet in these 

 the ascent of the sap is freest. And if we look out of 

 doors, I should say that the sap would be a slow traveller 

 if its ascent depended on wind and cold. Here, then, I 

 cannot back the favourite, and have a sort of blind leaning 

 for Turgesce7ice, or Swelling, a dark horse, certainly, and 

 I am all in the dark about him myself ; " and the author is 

 in a similar state of gloom upon other points besides. 



Practical Portrait Photography. By Wm. Heigh way. 

 (London : Piper and Carter, 1876.) 



The author of this little book of 152 pages has endea- 

 voured to " provide simple and intelligible rules of work- 

 ing," as he states in his introduction, so that those who 

 take up photography as an art should be helped over a 

 number of difficulties certain to occur, and not always 

 provided against in more ambitious works. The lessons 

 chiefly enforced are cleanliness and accuracy in preparing 

 the requisite solutions, and method in carrying out the 

 rest of the processes ; though these lessons may seem 

 trite to the regular student of science, they are no doubt 

 much needed amongst photographers who are not at the 

 same time practised chemists. 



The necessary instructions are well and carefully given, 

 and the author has omitted no point of importance, 

 taking the reader seriatim through every detail, from 

 cleaning the glass plate to finishing the paper print. 



We notice some errors in chemistry, where the author 

 has given reasons for some of the processes, which we 

 hope will be corrected in a future edition. R. J. F. 



LETTERS TO THE EDITOR 



[ The Editor does not hold himself responsible for opinions expressed 

 by his cotrespondefits. Neither can he undertake to return, 

 or to correspond with the writers of, rejected manuscripts. 

 No notice is taken of anonytnous communications.^ 



On the Discovery of Palaeolithic Implements of Inter- 

 glacial Age 



The opinion that paleolithic man was a post-glacial being has 

 been steadily losing ground among certain geologists whose 

 studies render their opinions of considerable weight. Mr. Pen- 

 gelly and Prof. Ramsay have stated their conviction that the old 

 stone folk may have witnessed the commencement of glacial 

 conditions, and have been driven south by the increasing severity 

 of the climate. Prof Dawkins has expressed his belief that 

 while our rude ancestors hunted the elephant, glaciers still lin- 

 gered in our mountain-valleys. Mr. Tiddeman goes further, and 

 ascribes -.to them an inter-glacial age, and, as it seems to me, 

 proved his point by the discover/ of implements and a human 

 bone beneath glacial-clay in the Settle Cave. Mr. James 

 Geikie boldly advanced the opinion that all our palosolithic im- 

 plements are of inter-glacial age, and an intimate ) nowledge of 

 the glacial beds and gravels of the central and easten counties 

 led me independently to a similar conclusion. In making this 

 last statement I particularly desire it to be understood that no 

 claim is preferred to the theory as my own, for while I was 

 almost fearful of my temerity in even thinking such things, my 

 friend Mr. Geikie had brought his great stores of knowledge to 

 bear upon the point, and has made it peculiarly his own. 

 Nevertheless the fact that two geologists working independently 

 in different districts should arrive at similar conclusions is no 

 mean argument in our favour. The evidence upon which my 

 convictions are based is given in my " Geology of the Fen- 

 land," and in my " Manufacture of Gun-tlints," &c., tobe shortly 

 issued by the Geological Survey, and in the forthcoming edition 

 of the "Great Ice Age." 



Mr. Geikie has proved, and the work of Mr. Tiddeman, 

 myself, and others, has confirmed the observations that the 

 glacial epoch, instead of being an uninterrupted period of cold, 

 was one of fluctuating climate, there being known at least four ice 

 ages with intervening cold, mild, and warm epochs. The greatest 

 severity of cold took place towards the early part of the Great 

 Ice Age, and the great chalky boulder-clay which extends 

 nearly to the Thames was then formed ; no subsequent ice- 

 sheet having left its traces further south than Lincolnshire. 

 Travelling northwards from East Anglia we find this boul- 

 der-clay running under the purple boulder-clay, and this 

 again overlaid still farther north by a yet newer glacial bed. 

 These are well-known facts accepted by all geologists, but as 

 the old chalky boulder-clay has unfortunately been named the 

 "upper" boulder clay, it has been supposed to mark the 

 close of the glacial epoch, whereas it is only " upper " so far as 

 East Anglia is concerned, and merely marks the last glaciation 

 of that area, the more northern districts having been more than 

 once glaciated since then. The East Anglian " upper " boulder- 

 clay is probably as old as the Lancashire "lower" boulder- 

 clay. 



In consequence of th:s confusion of terms, the beds which 

 overlie the chalky boulder-clay have been confidently relegated 

 to post-glacial times, whereas all that can be determined by this 

 superposition is that they are " post-boulder-clay." From valley 

 and other gravels occupying such positions, great numbers of 

 palaeolithic implements have been obtained, especially from the 

 basins of the rivers Lark and Little Ouse. Wherever bones 

 are found in these gravels they belong to what Prof. Dawkins 

 calls the pleistocene, and not to the pre-historic fauna j and this 

 mammalian fauna is continued into the estuarine gravels of the 

 Fenland, which contain extinct shell?, such as Cyrena Jltiminalis, 

 a shell which has often been found in gravels jieldmg palteo- 



