OS Scientific Intelligence. 



relation of atomic theories to the physical theories based upon 

 the properties of a continuous medium (the ether), such as the 

 prevailing theories of eleotromagnetism and of light. That some 

 reconciliation, or at least some adjustment, between the two points 

 of view has become necessary is plainly apparent nowadays to all 

 students of physics. It is perhaps the modern way of stating the 

 question which used to be called the problem of the relation be- 

 tween ether and matter. In the part before us, the electric atoms 

 (electrons and "archions") are considered ; and the two remain- 

 ing parts which are to complete the book will deal with the atomic 

 structure of radiation and of matter respectively. h. a. b. 



9. The Pressure of Light ; by J. II. Poynting. Pp. viii, 103. 

 London, 1910 (Society for Promoting Christian Knowledge). — 

 This little volume contains the substance of several lectures on 

 the pressure of light which have been given by Professor Poyn- 

 ting before various popular audiences. It is marked by the lucidity 

 and simplicity which are characteristic of the author, particularly 

 in the illustrative experiments which are described. The whole 

 of the text is untechnical and may be easily read by any one who 

 is interested in this important development of physical science ; 

 while for readers who desire to obtain some idea of the mathe- 

 matical theory of the subject, an appendix is provided in which 

 the necessary calculations are set forth. h. a. b. 



10. Physics ; by C. R. Mann and G. R. Twxss. Revised edi- 

 tion. Pp. 424; 220 figures. Chicago, 1910 (Scott, Foresrnan 

 and Co.). — This is a revision of a high school text-book which first 

 appeared about five years ago. The new edition differs from the 

 old both in subject matter and in method of presentation. In 

 accordance with the growing sentiment against the laws of acceler- 

 ated motion, the absolute units, etc., for high-school pupils, the 

 authors have endeavored to limit their choice of material to that 

 which would appeal to the pupils as significant and, by means of 

 numerous problems in which the mathematical difficulties are 

 reduced to a minimum, to assure the mastery of the subject mat- 

 ter. The text is divided into two parts, of which the first is 

 designed as a year's work to be of interest to everybody. The 

 second part provides for an amplification of the course to meet 

 the requirements of the College Entrance Board. Italics and 

 heavjM'aeed type emphasize the more important conclusions. 



D. A. K. 



11. The Principles of Electro-Deposition j by Samuel Field. 

 Pp. xv, 383 ; 54 tables'and 121 figures. New York, 1911 (Long- 

 mans, Green and Co.). — The aim of the author is to provide a 

 laboratory guide which shall give a thorough understanding of 

 the underlying principles of the subject, rather than to furnish a 

 mass of details of workshop practice but briefly treated. The 

 first seven chapters deal with cells, the properties of electric cur- 

 rents, principles of the dynamo and the arrangement of appara- 

 tus. Then follow four chapters on the preparation of materials 

 and solutions, eight chapters on the deposition of various metals 



