METEOROLOGY. 353 



and induction. (Annalen der Hydrograpliie und maritimen Meteorologie, 

 1884, p. Co.) 



311. Prof. James Ttiomson, of the University of Glasgow, read before 

 the Montreal nieetingof the Brit. Assoc., a paper on whirlvviudsand water- 

 spouts, in which he adheres to the old view that the diiuiuution of press- 

 ure observed at the center of a hurricane is the cause of the movement 

 of the wind, and queries whether it may not be possible for the low 

 pressure to be abated through the combined influence of rarefaction by 

 heat and the whirling motion. He also thinks that in great whirlwinds 

 the whirling motion may be propagated upwards to the top of the at- 

 mosj^here. He suggests that the dark clouds, and in tornadoes the pen 

 dent spout, may be due to the precipitation of moisture on account of 

 abatement of pressure due to centrifugal force and ascension above the 

 sea level. [Prof. James Thomson's publications on this subject date 

 from 1852, and especially 1857, but while his writings are always worthy 

 of attention, it would seem that these particular points have already 

 been clearly explained by other students of meteorology.] {Kature, 

 XXX, p. 048.) 



312. Prof. W. von Bezokl, of Munich, has studied the question of the 

 cold days in May. He finds that whenever high pressure prevails in the 

 west and lower juessure in the east, and especially in southeastern 

 Euroi^e, a cold j)eriod occurs, and that this distribution of pressure is 

 particularly liable to occur in May. If this characteristic distribution 

 fails, then the cold days also fail ; the explanation of the coid days is 

 therefore dependent upon the explanation of the occurrence of this distri- 

 bution of pressure. After studying the isobars of Europe, he concludes 

 that when in spring the warming of the northern hemisphere begins at 

 the south and oceans and continents interchange their relations with 

 reference to pressure and temperature, then the Balkan peninsula, to- 

 gether with the land between the Adriatic and Black Sea, plays the 

 part of a small continent. It is therefore warmed up Avith reference to 

 the surrounding region, experiences a low barometric pressure, and es- 

 pecially favors the development of storm-centers. These, therefore, cause 

 the cool northerly winds and the cold days of Germany. {Z. 0. G. M. 

 XVIII, p. 268.) 



313. Dr. Koppen, in reference to the cold days in May, states that 

 neither the explanations of Miidler, Erman, Sainte ClaireDeville, Ass- 

 maun, von Bezold, nor others seem to him to aflbrd any satisfactory ex- 

 planation of the question why the precise days from the 10th to the 13th 

 should have such a decided tendency to be abnormally cold. [Z. 0. G. 

 M., XIX, p. 133.) 



314. K. Billwiller states that he has been surprised that van Bebber, 

 in his essay on the cold days in May, has so strongly stated that these 

 always happened on definite dates, whereas Dove had so clearly proved 

 that they are not simultaneous in different localities, nor do they hap- 

 pen on a definite date at any one locality, whence Dove considers that 



S. Mis. 33 — -23 



