2o8 



NATURE 



[December \.\. i'h i 



the case of the so-called simple machines, all of them 

 considered as frictionlcss, is taken up. 



The last cha|)tfr of this section is devoted to an 

 elementary treatment of the laws of friction, the 

 rough inclined plane being used as an illustration. 

 As a frictionless machine is a mere mathematical fic- 

 tion, adopte<l probably with the idea of smoothinj^ 

 the path of the student, it is a pity that the author 

 did not in the chapter on friction take one of 

 the simple machines, say the screw, and show how 

 materially such a formula as that deduced in the 

 previous chapter for the relation of power to weight 

 is modified directly friction is taken into account, and 

 the problem chanj^ed from a mere exercise in applied 

 mathematics to the pmctical question a young engineer 

 is constantly calh'd upon to f.ice. It is doubtful if it 

 is beneficial to students to set them to work out 

 problems on frictionless machines. 



In part ii. dynamics is taken up — velocity and 

 acceleration ; the laws of motion and their application 

 to motion on rough planes, Attwood's machine, &c. ; 

 composition of velocities and accelerations are fully 

 discussed. The last three chapters treat of uniform 

 motion in a circle, work, and simple harmonic 

 motion. 



The author is to be congratulated on the excellent 

 series of e.xamples given at the end of each chapter. 



(2) Laboratory work on the testing^ of materials 

 forms an important part of the training given in 

 engineering colleges at the present day, and many 

 teachers and students have felt the need of a good 

 text-book on the subject. Mr. Smith has done excel- 

 lent research work on the effect of combined stress, 

 and has devised ingenious strain-measuring apparatus 

 for use in his researches, and he is now to be con- 

 gratulated on having written a book which will be 

 welcomed by all those who are engaged in the branch 

 '^f experimental work known as the testing of mate- 

 rials, whether they are students just beginning to feel 

 that they are entering upon a new field of fascinating 

 work, practical men engaged in the daily task of 

 commercial tests, or advanced students busy with 

 research work upon one or other of the difficult 

 problems which still require elucidation. The book 

 is well illustrated, and the illustrations are so drawn 

 that they show the essential principles of the machine 

 or apparatus, a matter of great importance to the 

 student who wishes to design similar appliances in 

 connection with his own experimental work; the 

 chapters on strain-measuring instruments and on 

 alternating stress tests deserve special praise in this 

 respect. 



In the last chapter the author has given valuable 

 advice and suggestions as to the best lines on which 

 experimental work can be carried out in college 

 laboratories, and a table of suitable experiments with 

 notes as to the necessary apparatus. The book con- 

 cludes with four appendixes, a bibliographv, and a 

 table of constants; the third appendix is devoted to 

 a discussion on all the recent researches on combined 

 stress, including the author's own work, and forms 

 one of the best summaries which have vet appeared 

 of the present state of knowledge on this important 

 question. T H B 



NO. 2198, VOL. 88] 



OVR BOOK SHELI 

 General Index to the Monthly iS'ottces uj the Koyal 

 Astrunomical Society, volumes liii. to Ixx., 1892- 

 1910, together with the General Index to Illustra- 

 tions in the Memoirs, volumes i. to lix., and the 

 Monthly Notices, volumes 1. to Ixx., 1822-1'* • ■ 

 appendix, List of Comets, 1892-1910. Pp. viii+ : 

 (London: K-- ■' V-"" w-' <--;-. ■■-. ■ f 



1 HIS index IN nil).' 01 I uiiu.uiK'iiUii niipoii.nii-)- ii, 

 workers in astronomy, and is a sequel to those \ 

 viously published for vols. i. to xxix. and vols. xx\ 

 lii. respectively; it is hoped in future to publish geii' 

 indices covering successive even pericxls of tw- 

 years. The arrangement of the present volume i: 

 the annual indices prepared by Mr. Wesley has 1 

 carried out by Mr. Levander, under the general d: 

 tion of the secretaries, and he is to be congratul 

 on the success attained. 



Many of the headings have, by reason of the \ 

 gress in astronomical work during the past tw- 

 years, had to be rearranged or modified, and 

 changes are carefully explained in the preface. I 

 present section dealing with the " Monthly Notii 

 takes up 168 pages, with something like forty r- 

 ences on each page, a tribute to the energy displ. 

 by the authors of papers as well as to the comp! 

 ness of the index. 



Mr. Knobel has prepared the index to the illu^;- 

 tions, and this should prove exceedingly useful, - 

 the items are arranged under subject headings, ^ 

 moon, planets, instruments, &c., the authors' nrc 

 being given in approximately the chronological o; 

 of the papers. 



Dr. Crommelin's appendix gives particulars of 

 the comets observed during the period 1892-1910. 1 

 mencing with an apparition of Barnard's perio<: 

 comet in 1892, and ending with Brooks's secrd 

 periodical comet 1910^. In view of the plenitud.' 

 comets during the present year it is interestin;.^ 

 note that the average number per annum, for i> 

 19 10 inclusive, works out at 47, the greatest nun- 

 being 10 in 1898. 



Many copies of the previous general indices rer 

 in stock, and will be presented to such institut 

 and observatories as receive the " Monthly Notl( 

 but have not the indices ; application should 

 addressed to the assistant secretary. 



Evolution, Life, and Religion: a Study. By the R' 

 E. B. Kirk. Pp. 321. (Glasgow : John Smith 

 Son, Ltd.; London: James Clarke and Co., n. 

 Price 5s. net. 

 The author of this book states his personal inter 

 tation of cosmic and human evolution, which he 

 siders from a philosophical and theological point 

 view. There has been material and spiritual pro§ ' 

 from the simplest forms towards those of ever-int 

 ing complexity, and the author interprets this 

 continued expression of the Logos. He illustrates 

 by a fundamental diagram which he calls the " Loc - 

 mirror." He has hold of the sound idea that si 

 tific and intuitive interpretations must be regarded - 

 complementary, not as antithetic, but his own persoii.ii 

 equation bulks so large that it is difficult for ' 

 reader to get alongside of him. As it seems to 

 Mr. Kirk intermingles different "universes of u.-- 

 course " in a manner which is always unprofitable, as 

 when he seeks to show that various fundamental 

 doctrines of theology are expressions of fundamental 

 laws of nature. 



We have great sympathy with the proposi- 

 tion that "the mental continuity of creation in our 

 world is as marked as the physical, and the lower 



