March 5, 1903] 



NA TURE 



4i, 



Interest and Education. The Doctrine of Interest and 

 its Concrete Application. By Prof. C. DeGarmo. 

 Pp. xiii + 226. (New York : The Macmillan Com- 

 pany, 1902.) Price 4s. £>d. net. 

 THE masters in English secondary schools have in the 

 past been a little impatient of philosophical treatises 

 dealing with the principles underlying educational prac- 

 tice ; they have been apt to recognise education as an 

 art, though unwilling to give attention to writers anxious 

 to formulate a science of education. While fond of in- 

 sisting upon the value to the teacher of individuality 

 and Ireedom of action, our schoolmasters have failed 

 to understand that until they have discovered and 

 can apply the principles of their art, they are mere 

 empirics, each knowing only what he has learnt from 

 personal experience. The greater attention given in 

 America and Germany to the training of teachers has 

 incidentally resulted in the growth of a body of able 

 men devoted to the study of educational science. Prof. 

 DeGarmo, of Cornell University, is one of these students 

 of pedagogic problems, and the book before us, with its 

 evidences of enthusiasm on every page, represents some 

 of his recent work. Taking Schurman's dictum as his 

 text, that " interest is the greatest word in education," 

 he shows how interest arises among primitive men, what 

 its object should be, how it can be made to assist in the 

 delimitation of the curriculum, and what relation it has 

 to methods of teaching. Prof. DeGarmo has no sym- 

 pathy with those intellectual aristocrats who cherish 

 archaic educational ideals and deny the badge of 

 scholarship to all who do not accept their estimate of 

 the value of Greek and Latin. He attaches as much 

 importance to rational instruction in science as to the 

 making of Latin verses — "the student in the scientific, 

 the technological or the commercial course is not inferior 

 to his brother in the arts course . . . difference is not 

 inferiority." He quotes approvingly, too, Lord Kelvin, 

 who has said, "the higher education has two purposes — 

 first, to enable the student to earn a livelihood, and 

 second, to make life worth living," and this book should 

 greatly assist teachers so to educate their pupils as to 

 make both these requirements possible of attainment. 



A. T. S. 



The Theory of Optics. By Paul Drude. Translated 



from the German by C. R. Mann and R. A. 



Millikan. Pp. xxi + 546. (London : Longmans 



and Co., 1902.) Price 155. net. 

 A very full account of the German edition of the above 

 work appeared in these pages rather more than two 

 years ago (October 18, 1900), under the title "A 

 Modern Text-book of Optics." To what was then said 

 little need be added. Prof. Michelson, in his preface 

 to the translation, expresses the facts when he 

 writes, " But no complete development of the electro- 

 magnetic theory in all its bearings, and no compre- 

 hensive discussion of the relation between the laws 

 of radiation and the principles of thermodvnamics 

 have yet been attempted in any general text in 

 English. " 



Prof. Drude's book fills the gap, and we may will 

 agree with Prof. Michelson in his opinion that by 

 making the book accessible to English-reading 

 students, the translators have done an important 

 service. 



The translation has been well done; to the English 

 reader the get-up of the book has an unfamiliar and 

 not quite pleasing appearance, due to its American 

 origin, and the illustrations of apparatus are not as 

 good as we are accustomed to see in books of the 

 class, but this does not reallv detract from the high 

 merit of the work. 



An index, which was wanting in the German 

 edition, has been added, but the references to original 



NO. 1 740, VOL. 6/] 



papers, especially papers of historic interest, are sin- 

 gularly incomplete. The book does not pretend to 

 develop the subject from the historic standpoint, it 

 is true, but still the omissions noted are very marked. 

 In spite of these, the book is of very real value, and 

 should be found on the shelves of every physical 

 laboratory. 



Lc Forse Idrauliche. By Ingegnere Torquato 

 Perdoni. Pp. 205 ; with four plates. (Milan : 

 L'lrico Hoepli, 1902.) 

 In a country like Italy, where coal has to be purchased 

 from abroad, the utilisation of natural sources of 

 available energy is an important problem. In this 

 volume the author gives in tabular form a list of the 

 principal water courses of the Italian mainland, and 

 estimates, so far as information will permit, the 

 amount of horse-power obtainable from these (a) 

 under normal conditions (" magra ordinaria ") and 

 (b) during the dry seasons of the year (" minima 

 magra "), exceptional droughts being excluded. Be- 

 tween these two limits, there is a large amount of 

 energy available during the greater part of the year, 

 which might be utilised if provision were made for 

 supplying the deficiency during the dry months, and 

 one method suggested is to apply this water power to 

 electric traction on the railways, supplementing it in 

 the summer by the use either of ordinary locomotives 

 or steam engines at the generating stations. Of 

 other sources of energy, the sea with its tides and 

 waves is considered, and even glaciers are men- 

 tioned in connection with the property that a cold 

 body may act as a store, if not of energy (as the 

 author implies), at any rate of availability. This 

 distinction between energy and availability might 

 with advantage be pointed out clearly in the intro- 

 duction, which deals with " the unity of concepts in 

 modern physics," but in which the part devoted to 

 matters thermodynamic is suggestive of Carnot's 

 caloric theory of the motive power of fire rather than 

 of the second law as modified by Clausius. 



De Ether. By Dr. V. A. Julius. Pp. 56. (Haarlem : 



De Erven F. Bohn, 1902.) 

 L'Etere e la Materia pond.era.bile. By Ingegnere M. 



Barbera. Pp. viii+ 134. (Turin : Bertolero, 1902.) 

 The first of these pamphlets consists of a discourse 

 given to a vacation class of teachers in April, 1902, 

 shortly before the death of the author. It was pub- 

 lished at the request of many members of the class, and 

 is as good a general historic account as could possibly 

 be given in so short a space of our knowledge of the 

 ether, considered with regard to optical phenomena, 

 starting with the corpuscular theory of Newton, and 

 tracing the various theories of Huyghens, Fresnel, 

 Cauchy, Lord Kelvin, Maxwell, Fitzgerald, Larmor, 

 Lorentz, and other writers. 



Signor Barbera 's book is of a very different nature. 

 In it he endeavours to account, without the use of 

 mathematical formula;, for the whole of the phenomena 

 of modern physics and physical chemistry, on the sup- 

 position that the ether like matter consists of an aggre- 

 gate of material particles, and that it differs from matter 

 only in its very small density and very great elasticity. 

 In the fifth paragraph he discusses the propagation of 

 transverse waves on the hypothesis that the ether is a 

 fluid. The motions which he describes in this connec- 

 tion are, however, well known to readers of hydro- 

 dynamical text-books as those produced by a sphere 

 moving or oscillating in liquid. The book is up-to-date 

 so far as the inclusion of recently discovered physical 

 phenomena is concerned, but no theories of the ether can 

 be adequately discussed in a pamphlet of this size and 

 character, however carefullv written. 



