B. TERRESTRIAL PHYSICS AND METEOROLOGY. 129 



temperature and other correlated phenomena, as, for in- 

 stance, the appearance of the auroras of the 4th of February, 

 1872, and the 4th of February, 1874. 3Ieteorol. Ital.^ -^PP-, 



1875. 



RAINFALL, WINDS, AND PRESSURE IN ITALY. 



The distribution of rain in Italy for the years 1871 and 

 1872 is the subject of an elaborate memoir by Denza, in 

 which, after a careful discussion of actual observations of 

 rainfall and evaporation over the whole of Italy, he considers 

 the theoretical question of the cause of the peculiarities of 

 the distribution of rain in Italy in general, and especially in 

 1872, and has elucidated the distribution of the winds in Italy. 

 Denza adds to the memoir on rainfall one on the distribution 

 of barometric pressure, as shown by the averages of 1870 to 

 1875. 3Ieteorologia Italiana, Supplement, 1875,41. 



THE BORA OF SOUTHERN RUSSIA. 



Baron Wrangell has written a very interesting paper on 

 the causes of the Bora, or northerly gales, at Noworossisk. 

 This place, situated on the Black Sea, would, it is said, have 

 the finest harbor in the East, were it not for its exposure to 

 the strong north winds. According to Wrangell, this wind 

 gains most of its force in that locality from the fact that it is 

 a cold wind flowing down the mountain-sides ; and as we can 

 not prevent cold dry air from becoming colder by radiation 

 under a clear sky, he proposes to diminish the violence of the 

 wind by cutting a passage through a spur of the mountain in 

 such a way as to relieve the mass of air behind from any con- 

 finement whatever, so that the moment a slig:ht increase of 

 density takes place that air will flow away quietly through 

 the artificial valley. The approximate formula deduced by 

 him for computing the velocity of the wind, when the tem- 

 perature of the air and the barometric pressure are given, is 

 derived from an ingenious course of reasoning, and gives a 

 close approximation to the observed true velocity. WikVs 

 Mepertorium, 1875. 



FREQUENCY OF THUNDER-STORMS IN EUROPE. 



An investigation into the fi-equency of thunder-storms dur- 

 ing the summer months in Europe has been made by Von 



F2 



