INDUSTRIAL PROGRESS DURING THE YEAR 1876. xli 



of pressure in the atmospheric strata during storms, and shows that 

 according to the direction of the wind and the condition of the 

 barometer as to rising or falling very marked deviations may be 

 noted at moderate altitudes from the normal distribution of press- 

 ure. For instance, during easterly winds in Belgium, the barometer 

 at the upper station is low^, during westerly winds it is high. 



Von Bezold has published a second memoir on the phenomena of 

 thunder-storms in Eurojie, in which he shows that there is a pretty 

 well marked double maximum during the summer months in the 

 northern hemisphere, and that these maxima are the better distin- 

 guished from each other in proportion as w^e go farther away from 

 the equator ; wherefore he suggests that they may be considered as 

 due to the existence of the two summers of equatorial regions, or, in 

 other words, that they follow the tw^o passages of the sun across the 

 equator in the course of the year. 



The diurnal variability of temperature has been investigated by 

 Hann, who has extended his observations to a large number of sta- 

 tions scattered throughout Europe and Asia, He shows that the 

 daily variability reaches its maximum in the interior of North 

 America, A second region of maximum is found in Western Siberia, 

 at a higher latitude than in America. 



The shores of the Caspian and Baltic are visited by storms of 

 fierce northerly wdnds, precisely similar to the " northers " of the 

 Texas and Mexican coasts, A detailed study into the phenomena 

 of the Bora, as it is called, at Novarussisk, has been published by 

 Laron Wrangell, According to him, the violent wdnds that visit 

 this fine harbor acquire their force from the fact that they consist es- 

 sentially of cold dense air, wdiich descends the mountain-sides. He 

 calculates theoretically the violence of the wind ; and having shown 

 the satisfactory agreement of his formula wnth actual observation, 

 concludes that his explanation of its origin must be accepted, and 

 thence is led to propose a method by which the harbor may be pro- 

 tected, or, rather, by which the wind itself may be diminished, if not 

 prevented. 



The movement of water in rivers has been the subject of a series 

 of very extensive experiments by Captain Allen Cunningham, of 

 India, and his work ranks in importance with that of Humphrey 

 and Abbott, and the recent investigators in Europe. 



An excellent memoir has been published by Dr. Armieux on some 

 results of observations made on the Pic du Midi, and especially on 

 the presence of red snow in the Pyrenees, and on the general history 

 and condition of the question as to the exact nature of this phe- 

 nomenon. 



The formation of snow crystals has been observed by Tissandier 

 in a balloon ascension : he notes that a stratum of warm air accom- 

 panied the thin stratum of ice crystals; the higher temi3erature was 



