190 Scientific Intelligence. 



Abraham supposes electrons unchanged by velocity, while the 

 Lorentz-Einstein theory is based upon the relativity principle. 

 E. Hupka in his investigation endeavors to decide which theory 

 is the most probable. The article is interesting principally from 

 the view of technic : for the author describes minutely the method 

 by means of which he excited electron streams in high vacua. 

 Although he did not attain to the velocity of the fi ray, he suc- 

 ceeded in producing rays of great homogeneity, suitable for meas- 

 urement. The vacua were produced by liquid air and the use of 

 charcoal, and he used potentials as high as 90,000 volts. The 

 paper contains many tables and plotted charts, giving compar- 

 isons of results on the Abraham or solid sphere theory and the 

 Lorentz-Einstein relativity principle. The measurements agree 

 better with the latter theory than with the sphere theory of 

 Abraham. — Ann. der Physik, 1910, No. 1, pp. 169-204. 



J. T. 



9. Hertz's Photoelectric Effect. — M. Eugene Bloch criticizes 

 the conclusion that this effect coincides in greatness with the 

 Volta series, the metals, more photoelectric, being the more 

 electropositive, and believes that the order can be reversed when 

 one passes from one wave length to another. — Comptes Rendus y 

 Dec. 13, 1909, p. 1110. j. t. 



10. Influence of Thunder on Size of Raindrops. — V. J. Laine 

 has studied the changes in rainbows which apparently follow 

 peals of thunder. He describes as follows a typical case : Between 

 six o'clock and five o'clock in the evening he observed in the East 

 a rainbow accompanied by a secondary bow. During thunder the 

 colors of both bows trembled to such a degree that the color 

 limits and the edges of the bows were entirely weakened, and 

 one observed very quick vibrations over the entire rainbow. This 

 occurred with each peal of thunder. The change in color Laine 

 attributes to changes in size of raindrops. The size before peals 

 of thunder was under 0'l mm , and during the thunder it increased 

 to 0*5 mm and to l mm . The author attributes the change to the 

 acoustical vibration of the thunder. — Physikal. Zeitschrift, Dec. 

 1, 1909, pp. 965-967. J. t. 



11. Conduction of Electricity through Gases and Radio- 

 activity ; by R. K. McClung. Pp xvi + 245. Philadelphia, 

 1909. (P. Blakiston's Son & Co.) — This is a "text-book with 

 experiments" designed to introduce college classes to the fasci- 

 nating and important subjects indicated by the title. There has 

 been so great a development during the past twelve years in our 

 knowledge of the ionization of gases and the properties of the newly 

 discovered radiations that ample material exists for an interesting 

 and instructive course for students. The present book is the 

 first to be written with this end in view, and it seems well adapted 

 to the purpose. The descriptive portions though very concise 

 are fairly satisfactory and many useful directions are given for 

 performing experiments in this field. h. a. b. 



