72 Scientific Intelligence. 



posed to be able to carry electrical charges as in the case of 

 electrolytes. Lorentz explains electrical phenomena by the group- 

 ing of corpuscles, and supposes the undulations of light to be the 

 vibration of the ions. It is interesting that he predicted a phe- 

 nomenon similar to that discovered by Dr. Zeeman. j. t. 



11. Application of the Rontgen Rays to Surgery. — The recent 

 numbers of French Scientific Journals contain many articles on 

 the application of the X-rays to surgery. M. Oilier describes his 

 researches upon the osseous regeneration in man after surgical 

 operations. Observations hitherto on this subject have been very 

 difficult, and one had to study the cases after death. The X-rays 

 now permit an exact study of the form of the osseous develop- 

 ment, and in certain cases render unnecessary the amputation of 

 diseased limbs, since the diseased portions can be now accurately 

 located and removed. — Comptes Rendus, No. 20, May 17, 1897. 



J. T. 



12. Transparency of Ebonite. — M. Perrigot, in a note pre- 

 sented to the Academy by M. Mascart, states that plates of 

 ebonite ()-5 mm thick are transparent to red light ; light passing 

 through plates 2 mm thick also affects orthochromatic plates. — 

 Comptes Rendus, No 20, May 17, 1897. j. t. 



13. The Theory of Electricity and Magnetism, being Lectures 

 on Mathematical Physics • by Arthur Gordon Webster ; pp. 

 576, 1897. (The Macmillan Company.) — This extensive text 

 book on the mathematical theory of electricity is designed espe- 

 cially for the use of advanced students in our American colleges, 

 and is intended to embody the improvements and additions which 

 have been made in this domain of science since the time of Max- 

 well's famous work. These additions, derived from the labors of 

 Helmholtz, Hertz, Heaviside and others, are carefully and instruc- 

 tively indicated. An effort to employ a consistent and convenient 

 notation throughout seems to have been pursued with success, for 

 which the author will surely deserve the thanks of his readers. 



Professor Webster's experience has taught him that few stu- 

 dents who have received only undergraduate instruction in mathe- 

 matics are sufficiently advanced to enter at once upon the subject 

 of mathematical physics. Hence, to quote from his preface, "I 

 have therefore considered it expedient to prefix a mathematical 

 introduction giving a short treatment of the important subjects 

 of Definite Integrals and of the Theory of Functions of a Com- 

 plex Variable, indispensable to a study of the Potential Function. 

 For the same reason, I have included a treatment of the funda- 

 mental principles of Mechanics ab initio, including the deduction 

 of the Principle of Energy, Hamilton's Principle, and Lagrange's 



Equations ot Motion In this manner it has come about 



that the book is nearly half finished before the word Electricity is 

 mentioned. This may be objectionable to some persons, but I 

 consider it of great importance that the student should be well 

 supplied with tools and practiced in their use before he is called 

 upon to use them on a new and unfamiliar subject Thus 



