﻿164 Notices respecting New Books. 



Geitel on the dependence of the photo-electric effect on the orien- 

 tation of tbe plane of polarization of the light, are sufficiently in 

 the subject of physical optics and of a teaching order and experi- 

 mental beauty to justify their inclusion here. A little might well 

 have been said in reference to the experiments of EitzGrerald and 

 Trouton on the plane of polarization of electromagnetic waves, 

 seeing that the results of these and similar investigations are, of 

 course, assumed in the book. There appears to be some confusion 

 about the statement on page 90 as to what is given in tables of the 

 optical properties of different kinds of glass. Not the relative 

 dispersion, but the reciprocal of the dispersive power is given in 

 such tables as we have seen ; and this is "what the formula on p. 90 

 should be called. J. J. 



The Kucleation of the Uncontaminated Atmosphere. By Carl Barus. 

 Hazard Professor of Physics, Brown University. Washington, 

 D.C. : Published by the Carnegie Institution of Washington, 

 1906. Pp. xii + 152. 



This monograph contains an account of experiments and obser- 

 vations carried out with the object of obtaining a continuous 

 record of the nucleation of the atmosphere in localities relatively 

 free from the habitations of man, and therefore free from nuclea- 

 tions of local and artificial origin. The observations were made 

 at two stations, Providence and Block Island, simultaneously and 

 with similar apparatus. In addition to the tabulated results and 

 the conclusions to be drawn from them, the monograph contains 

 an account of various experiments on the distribution of the nuclei, 

 the numbers and gradations of size of the efficient nuclei in dust- 

 free air, and the critical conditions in the formation of ions and of 

 nuclei. 



Derniers Progres du Telpherage Electriqiie. Par Emile GtUARIni, 

 Professeur a, l'Ecole d'Arts et Metiers de Lima (Perou). Paris : 

 H. Dnnod et E. Pinat. 1906. Pp. 27. 



The telpherage system of transport is one well adapted to new 

 countries, where the cost of constructing a railway for the same 

 purpose would be prohibitive. The author of the small pamphlet 

 under review gives a very useful account of some of the more 

 recent examples of the telpherage system as practised in the 

 United States, and the booklet should prove valuable to those 

 interested in the subject. 



