Notices respecting New Books. 141 



A Laboratory Course in Experimental Physics. By W. J. Loudon, 

 B.A., and J. C. McLennan, B.A. JNew York : Macmillan & 

 Co., 1895. 



Although text-books of practical physics are now fairly numerous, 

 the demonstrators in physics of the University of Toronto appear 

 to have found it impossible to adapt any of the existing ones to 

 the requirements of their students. The same difficulty has been 

 experienced in most English laboratories, partly on account of the 

 diversity which exists between the apparatus of the various 

 institutions, and partly because of the different aims of students 

 working in them. Consequently nearly every laboratory possesses 

 instruction-sheets, either in print or manuscript, which have in 

 some instances been edited and issued in book form ; the present 

 volume is a case in point. 



The experiments described in the book are arranged in two 

 courses, elementary and advanced, in the former of which 

 weighing and measuring, light and heat, are included, while the 

 advanced course consists of sound, advanced heat, electricity, and 

 magnetism. Some easy experiments in electricity and magnetism 

 might have been included in the elementary course, otherwise the 

 selection is a fairly good and useful one. The section on sound 

 contains figures and descriptions of Helmholtz's and Konig's 

 apparatus for various experiments, but many students' laboratories 

 in this country are, unfortunately, not equipped with large 

 electrically- driven tuning-forks and chronographs. Experimental 

 details are sometimes omitted ; for example, in describing the use 

 of the spectrometer as a goniometer, the student is not told how 

 to focus the telescope and adjust the slit so as to obtain a parallel 

 beam of light from the collimator. In the same experiment it is 

 erroneously stated that the edge of the crystal must coincide with 

 the axis of the instrument, whereas the two need only be parallel 

 to each other if the collimator is properly adjusted. Again, in 

 calorimetric measurements, errors arising from radiation between 

 the calorimeter and its surroundings are not very adequately 

 discussed; the calorimeter is supposed in all experiments to alter 

 its temperature at a uniform rate, and matters are so arranged 

 that the mean between its initial and final temperatures is that of 

 the atmosphere. In specific heat determinations a preliminary 

 experiment is necessary in order to satisfy the latter condition, 

 and the assumption of uniform rise of temperature is only approx- 

 imately true, even when the body under experiment is a good 

 conductor of heat. 



The book is printed in a bold, clear type, and its illustrations 

 are good ; it will be found a useful addition to the laboratory 

 bookshelf. James L. Howard. 



