Chemistry and Physics. 395 



Ph.D. 8vo, pp. viii, 322. New York, 1899 (The Macmillan 

 Company). — In this book the author has attempted a somewhat 

 condensed review of the progress in physical science from the 

 earliest times to the present. In the preface he quotes Ostwald's 

 statement to the effect that a defect attaching to present scien- 

 tific education is the absence of the historical sense and the want 

 of knowledge of the great researches upon which the edifice of 

 science rests. It seems to be fully recognized that the historical 

 development of a subject is an essential aid to the proper under- 

 standing of it. It may be a question, however, whether this his- 

 torical treatment should not be given in connection with the subject 

 discussed rather than have a separate course devoted to it. In this 

 book the history of physics is divided into time epochs, i. e., that 

 of the Greeks, the Romans, the Arabs, the Middle Ages, the 

 Renaissance, the Seventeenth Century, the Eighteenth Century 

 and the Nineteenth Century ; closing with a chapter on the Evo- 

 lution of Physical Laboratories. This method seems to necessi- 

 tate considerable repetition, light for example being considered 

 six times. Possibly a physical classification would entail less 

 repetition and be handier for reference. A wide range of refer- 

 ences has been made use of and these are given in foot-notes. 

 The book will undoubtedly be of use to students and teachers of 

 physics, for whom it was intended. 



6. The Electrolytic Interrupter. — Much interest has been ex- 

 cited by Dr. A. Wehnelt's new interrupter for induction coils, 

 which consists of a lead plate, the cathode, and a platinum point, 

 the anode, immersed in dilute sulphuric acid and connected with 

 an electrical source of comparatively high voltage. At a recent 

 meeting of the Physical Society in London, March 10, Mr. A. A. 

 Campbell Swinton described his experiments with this inter- 

 rupter. It was found that the minimum working voltage was 

 twenty-five volts. The spark-pitch varied with the length of the 

 platinum terminal wire. The wire must be immersed in the 

 dilute acid before the circuit is closed, otherwise the action is not 

 obtained. The interrupter becomes fatigued in a quarter of an 

 hour and then the platinum becomes red-hot. The interrupter 

 would be very effective for X-ray work if it did not heat the 

 Crookes tubes. Mr. Swinton suggested the use of the interrupter 

 for the production of Hertz waves. Professor Oliver J. Lodge 

 thought that it would not be effective for this purpose since the 

 air would not quickly regain a non-electric condition. The 

 interrupter will work with an alternating current but with half 

 the efficiency, apparently allowing only one-half the alternations 

 to pass. A well-known arrangement, however, of circuits might 

 give a greater efficiency. — Nature, March 16. j. t. 



7. Measurement of slow electrical oscillations. — W. Konig dis- 

 cusses previous methods of receiving the sparks from an induction 

 coil on lamp-blacked rotating discs, and describes an efficient 

 method of measure, which consists of a tuning fork provided 

 with a stylus which serves both to register the time on a blackened 



