PHYSICS OF THE GLOBE. 83 



side northward or on the south side eastward. The most 

 of the centres of low pressure that follow the north coast 

 of Norway turn east and southeast and pass on to the north 

 of Nova Zembla into Russia. The other important storm- 

 path is up the east coast of Greenland, west of Iceland, Jan 

 Mayen, and Spitzbergen, then suddenly eastward to the north 

 coast of Nova Zembla. The storms that pass up the west 

 coast of Greenland are not felt at all on its east coast. 



Miihry (Petermann's Mittheilungen, 1877, 21), from the 

 study of three westerly storms in Europe in 1873 (i. e., Jan- 

 uary 23, March 11-13, December 16-19), concludes that these 

 represented great equatorial currents penetrating from the 

 Atlantic eastward deep into the interior of the cold region 



of Asia. 



OPTICAL PHENOMENA. 



The application of the spectroscope to the study of the 

 atmosphere continues to be urged in a desultory way by 

 Professor Smythe, who notes the occurrence of a severe rain 

 on August 21, 1877, "marked by a heavy rain band in the 

 prismatic spectrum of the daylight." The studies of Hen- 

 nessey upon the atmospheric bands at the time of sunrise 

 and sunset give, however, the proper clue as to the best 

 method of making and utilizing this class of observations. 



In discussing a larsre number of accurate observations of 

 the scintillation of the stars, Montigny is led to the conclu- 

 sion that the intensity of this phenomenon increases with 

 the approach of rainy weather or moist weather at all sea- 

 sons. The increase is noticeable one or two days before the 

 rain arrives, and diminishes immediately after the rain ceases. 

 When a barometric depression with strong winds passes near 

 the observer, the scintillation is remarkably increased. 



Lommel, after calling attention to the knowledge pos- 

 sessed by Biot, Brewster, Goethe, Arago, and Billet in refer- 

 ence to the polarization of the light of the rainbow, shows 

 that the so-called Cartesian angle of incidence is that for 

 which, for every substance and every color, according to 

 FresnePs theory, one ninth of the light polarized perpendic- 

 ular to the plane of incidence will be reflected. For the 

 whole rainbow the effectual rays are those that possess the 

 maximum polarization. For a single prism the angle of 

 minimum deviation corresponds to that of minimum polar- 

 ization. 



