;o2 



NA TURE 



[January 14, 1909 



for example, caji be at once drawn by erectinpf an 

 ordinate at the junction of the diagonal of the same 

 bav with the bottom boom, equal to the product of 

 the two parts into which the junction point divides 

 the span, and joining the end of the ordinate with 

 the ends of the span. An equally simple construction 

 gives the line for any member of the bottom boom, 

 and the influence lines for all the diagonals can be 

 drawn by first drawing two parallel lines through 

 the ends of the span ; then if verticals are drawn 

 through the end points of any bay to meet these 

 respective lines, and the two points of intersection 

 are joined, the line thus drawn, together with the two 

 parallel lines, is the " influence line " for the given 

 bav. 



Part vi. is devoted to the description of, and calcula- 

 tions for, types of German, English and American 

 cranes. This part of the book is particularly valuable, 

 as theory and practice supplement each other in a way 

 that is really helpful to designers. The last three 

 sections are devoted to specifications, useful tables, 

 and a valuable index to articles and papers on cranes. 

 The book is excellently printed and well illustrated 

 on very stiff paper. It can cordially be recommended 

 to designers, builders, and users of all kinds of lifting 

 and carrying machinery, and we can hardiv think of 

 a branch of mechanical engineering in which the book 

 will not prove u.seful for reference. .Students will also 

 be well repaid by a careful study of the designs given 

 and the calculations therewith, as they will be able to 

 appreciate, perhaps, better than in any other way, 

 the limitations of the theories upon w hlcli tliey are apt 

 to place implicit trust. K. C. L. 



AN OXFORD CH.IMPIOX OF DARWINISM. 

 Essays on Evuhilioii, 1889-1907. By Prof. E. B. 

 Poulton, F.R..S. Pp. xlviii-t-^8o. (O.xford : Claren- 

 don Press, igoS.) Price 12s. net. 



/~\N July I, 1858, an epoch in the history of science 

 Vy was created by the reading, before the Linnean 

 Society of London, of the papers by Darwin and 

 Wallace on natural selection; and on July i, ujo8, 

 the fiftieth anniversary of this momentous occasion 

 was appropriately celebrated under the auspices of the 

 same society. The publication of Prof. Poulton 's 

 volume is especially well timed, for it appears while 

 the Darwin-Wallace commemoration is fresh in the 

 minds of all, and while the weighty utterances by 

 which the veterans Wallace and Hooker themselves 

 so greatly added to the interest of the proceedings 

 on that occasion are still a recent memory. 



.--Vmong those men of science who have found their 

 chief inspiration in the work of Darwin and Wallace, 

 no one has laboured with greater perseverance and 

 success than Prof. Poulton, a]id the present collection 

 of essays embodies the main results of his investiga- 

 tions during his tenure of the Hope chair at Oxford. 

 The memoirs have all in one form or another appeared 

 before, but ' the author is not by any means content 

 with a mere reprint of his former publications; he 

 has, on the contrary, spared no pains to bring the 

 treatment of his various topics up to date, and a 

 NO. 2046, VOL. 79] 



comparison with the lectures and addresses in their 

 original form will show that in many cases this must 

 have involved considerable labour. But with so fertile 

 and so rapidly growing a subject as that which Prof. 

 Poulton has made his own, a period of nineteen years, 

 which is that which separates the first essay in point 

 of date from the present time, gives opportunity for 

 enormous accessions of material, and almost inevit- 

 ably involves some modification, if not in the principles, 

 at least in the details of interpretation. The author 

 has acted fairly towards his readers by ensuring that 

 the essays here reprinted, though preserving the 

 general form and tone in which they were originally 

 framed, should nevertheless be the expression of his 

 own present views, and should embody the principal 

 points of evidence that have since come to light. 

 The kevnote of the book is the all-importance of 

 natural selection, as propounded by Wallace and 

 Darwin, in the interpretation of the past history and 

 present condition of organic nature. The essays form 

 a powerful reinforcement of what is properly and 

 distinctively called the Darwinian theory of evolu- 

 tion, and should tend to reassure those weaker 

 brethren who have allowed themselves to be persuaded 

 or terrified into losing confidence in the work of the 

 two great founders of rational evolutionary doctrine. 



The greater number of Prof. Poulton 's arguments 

 and illustrations are naturally drawn from the wonder- 

 fully rich domain of insect bionomics. The way in 

 which the great Oxford collection, so liberally estab- 

 lished by Hope, and so assiduously tended by West- 

 wood, has been made of late years to subserve the 

 cause of .scientific research and progress, especially in 

 the unravelling of intricate problems of evolution, is 

 one of the most remarkable features in the recent 

 history of the University. The development of such 

 studies in Oxford, of which the present volume is 

 only one among many manifestations, should be a 

 matter of cordial congratulation to the present Hope 

 professor, on the part, not only of entomologists, but 

 of all who take a rational interest in any depart- 

 ment of biology. 



Space would fail us in the attempt to give an 

 adequate account of the contents of this stimulating 

 book. A bare enumeration must sufiice. First comes 

 a discussion upon the age of the earth, comforting 

 to those biologists who have been disturbed by certain 

 physical calculations now in great measure aban- 

 doned. Next we have the question asked and 

 answered, " What is a species? " Essays follow on 

 the theories of evolution which rival or antagonise 

 Darwin's, on the nature of heredity, and on the re- 

 markable anticipation of Galton and Weismann by 

 the anthropologist James Cowles Prichard. The 

 Birmingham lecture on Huxley is of especial value, 

 as it not only defines and accounts for the precise 

 attitude of that great biologist towards the Darwinian 

 theory, but also contains one of the most forcible and 

 convincing pleas that we have yet seen for a more 

 rational use in education of our present system of 

 examinations. The three concluding essays, which 

 show an immense command of facts, deal in a 

 masterly manner with the fascinating subject of 

 mimicry. They are especially remarkable as in- 



