204 



NATURE 



[July 1 6, t874 



that he says anything peculiarly novel, but he treats the 

 subject so plainly and in so much detail, that prac- 

 tical use can be made of his directions on a hitherto 

 too much neglected point in rural economy. 



In Chap. IV. e.xamples are given of successful farming, 

 both in large and small holdings, which all interested 

 would do well to peruse. With industry and skill based 

 on scientific knowledge, the productive pov.er of the soil 

 is astonishing. We sec this more especially in the arid 

 and sandy ground in Belgium, where two or three acrei^j 

 produce is sufficient for the support of a family. Steam 

 ploughing, no doubt, is an equivalent for spade husbandry 

 in stirring and pulverising the soil, but the personal exer- 

 tions and superintendence of the cottager in thorough 

 tilling, in careful seeding, successive cropping, manuring, 

 weeding, and harvesting, cannot be excelled or equalled in 

 substantial production. There is, moreover, in Scotland 

 at all events, a degree of comfort and healthy sturdy 

 appearance among that class, now perhaps too limited in 

 number, which bears a striking contrast to the beer- 

 drinking artisan and his wan shrivelled children in towns. 



The author concludes with a chapter on cottage- 

 gardening, which may be profitably studied by those 

 of more pretension than the mere cottager. In Eng- 

 land the taste for decoration and utility in small garden- 

 ing is much more manifest than in Scotland, where 

 little else than Scotch kail and Weeds are, as a rule, to be 

 seen. Mr. Baldwin has, on the whole, done ample jus- 

 tice to the various subjects he has treated, while the scope 

 of his work is sufficiently comprehensive for the guidance 

 of those who need instruction ; and most farmers do, be 

 their rural occupation of small or large compass. 



We hope that the spread of works of this class will pave 

 the way for the general circulation among farmers of 

 works of a much more technical and scientific kind, 

 and that ere very long, through the exertions of the Agri- 

 cultural Societies, both of England and Scotland, Agri- 

 cultural Schools will be established in convenient centres 

 both in England, Scotland, and Ireland, by means of 

 which the British farmer will be at least on as good a 

 footing as the farmer on the Continent of Europe and in 

 America. I 



OUR BOOK SHELF 



Elftiidiitary Dynamics, with numerous Examples. By 



W. G. Willson, M.A. (Calcutta : Thacker, Spink, 



and Co.) 

 Principles of Mechanics. By T. M. Goodeve, M.A. 



(Longmans' Text-books of Science.) 

 The first work on our list does not aim at a novel expo- 

 stion of principles, though it differs from the ordinary 

 text-books in use amongst junior students. Notes ori- 

 ginally put together by the author for the use of pass 

 students of the Calcutta University have, after some con- 

 siderable trial of their merits, been put together in the 

 present form so as to embrace all the parts of the sub- 

 jects which arc generally treated of in text-books. 



Mr. Willson is an ardent admirer of the works by Pro- 

 fessors Thomson and Tail ("the magnificent treatise on 

 Natural Philosophy," " the reader who wishes for further 

 information on this subject (and on all such subjects) is 

 recommended to consult," &c.), and his principal aim has 

 been, we expect, to render the views of these distinguished 

 writers more accessible to junior students. Knowing how 

 liable autboj-f are to go to pieces oii the kinematic rocks, 



we have gone as c^ircfully as we could through the text, 

 and it appears to us that the author not only understands 

 his subject, but has manifested ability in presenting his 

 material in a clear form to his readers. Dynamics he 

 subdivides into statics and kinetics. In both these 

 branches he adopts for unit of force the kinetic unit for 

 which the pound avordupois is the unit of mass. We 

 may remark in passing, that this is the only elementary 

 book we know which goes fully and carefully into the 

 subjects of the several units. Under the head of statics, 

 the writer treats of force at a point, of parallel forces, of 

 moments, of centre of gravity, resisting forces, machines. 

 and of work and energy ; under the head of kinematics, 

 we have velocity, accelerated velocity, and kinemitical 

 principles and methods ; under kinetics, we have dyna- 

 mical laws and principles, the force of gravity (falling 

 bodies, motion on an inclined plane, Attwood's machine, 

 &c.), collision of bodies, and energy. On p. 130, the term 

 Roman steelyard is derived from Ruman, an Arabic word 

 for a pomegranate, ''and the shape of the counterpoise 

 seems to have given rise to the name." There are a great 

 m,iny examples, many very familiar to us, given at the 

 end of the various chapters. The author apologises for 

 imperfections in type and diagrams, but he need hirdly 

 have done so ; we have seen worse diagrams in text- 

 books got out nearer home. .Some typographical blun- 

 ders we have detected, but the context will enable a 

 reader to correct them. The work has no index, is of a 

 handy size, and gives one a favourable impression of the 

 sort of training provided for the Calcutta students. 



Mr. Goodeve's name is sufficient warrant for the accuracy 

 and thoroughness of any work on mechanics that bears it 

 on its title-page. Mis style is very lucid, and the accuracy 

 and fulness of his knowledge of his subject enable him 

 to give just sufficient explanation and yet not be too con- 

 cise. He aims at a different class of students than that 

 we have had t^ consider in the former part of our notice. 

 These Text-books arc designed for the '' self-instruction of 

 working men,'' and the two works by our present author 

 in this series seem to us just fitted for them. In the work 

 before us we are taken over a wide field. In an Intro- 

 duction of sixty pages we have a miniature treatise, the 

 representation of force, the gravitation measure of force, 

 the laws of motion, and the meaning of the term energy, 

 /w/tv (;//(!, are discussed. In the remaining twelve chap- 

 ters most of the ground gone over in the first-noitei 

 work is gone over rapidly here, and copious application 

 of the prmciples is furnished by the description of a num- 

 ber of machines, the bare enumeration of the names of 

 which would furnish an ordinary ''Bookshelf" notice; 

 in addition we have an account of the equilibrium and 

 pressure of lluids and of gases, of the hydraulic press and 

 hydraulic cranes, a chapter on girder beams and bridges, 

 the strength of tubes and the catenary, all treated without 

 reference (except in one or two places) to the calculus. 

 We have much pleasure in commending this recent 

 addition to the series, with its clear type and numerous 

 and excellent diagrams, to all who take an interest in me- 

 chanical applications. There are many excellent exer- 

 cises scattered throughout the work. 



LETTERS TO THE EDITOR 



[T/ie Editor does not hold himself risponsible for opiiiioits expressed 

 by /lis eorrespoiiJciits. No notice is taken of anonymous 

 coinnitinicatioiisi\ 



The Degeneracy of Man 

 In Nature, vol. x. p. 147, Mr. Edvv.ira B. Tylor writes : — 

 " It would be well worth while if Dr. Peschel, from personal ' 

 or published sources available tu him, would settle once for all 

 the question whether the great Bavarian ethnologist (Martins) 

 continued through life the degenerationist that we in England 

 suppose him to have been." 



