552 Scientific Intelligence. 



between the displaced lines in the region near the cathode and at 



£ 



a distance. The value of — =10 4 has obtained from the canal 



m 



rays.— Ann. der Physik, No. 5, 1910, pp. 890-918. j. t. 



6. Effect of Dust and Smoke on the Ionization of Air. — From 

 the investigation of A. S. Eve, of McGill University, it appears 

 that " the presence of dust, smoke, mist or other centres charged 

 or neutral in the air causes a transformation from small to 

 large ions. In this way, the total number of ions present may 

 be increased, while the conductivity is diminished. In any 

 region of air where a charge of one kind is predominant, the 

 effect of the presence of centres, neutral or charged, is to increase 

 and accentuate the excess. This tendency must have an important 

 influence in the variation of the potential gradient and on the 

 production of thunder storms." — Phil. Mag., May, 1910, pp. 

 657-673. j. t. 



7. Measurements in the Extreme Infra- Red Spectrum. — II. 

 Rubens and H. Hollnagel show that the interferometer method 

 is preferable to the diffraction grating method in the study of the 

 infra-red region. They have employed a quartz-plate inter- 

 ferometer with " Reststrahlen " and have determined the wave 

 lengths and energy distributions of the Reststrahlen of rock salt, 

 sylvine, potassium bromide and potassium iodide and have obtained 

 a relation between the molecular weight and the mean wave 

 length. The index of refraction of water for A =82*3 /j. is of the 

 same order as in the visible spectrum. By the investigation of 

 Reststrahlen the optical spectrum has been extended 2/3 of an 

 octave. Its complete extent is now 10 octaves — two of which 

 are in the ultra-violet, one in the visible and seven in the ultra- 

 red.— Phil Mag., May, 1910, pp. 761-782. j. t. 



II. Geology. 



1. Paleogeography of North America j by Charles Schu- 

 chert. " Dedicated to those two great leaders in Geology and 

 Stratigraphy, James Dwight Dana and Eduard Suess." Bull. 

 Geol.'Soc. Amer., vol. xx, pp. 427-606, pis. 46-101, 1910. Pre- 

 sented before the Society December 30, 1908. — With due regard for 

 the other important contributions to paleogeography which have 

 appeared during the course of the past generation and especially 

 within the past few years, this may still be held the most import- 

 ant single contribution to the subject which has yet been pub- 

 lished. Working for many years in the front rank of invertebrate 

 paleontologists, the author's interests have broadened beyond the 

 organisms to the inferences which their relationships imply as to 

 the extent, connections, and durations of the continental seas. 

 Although the concurrence of conclusions from several branches 

 of geologic knowledge is required to attain reasonably safe 



