286 METEOROLOGY AND ALLIED SUBJECTS. 



is formed from a collection of radiating snow crystals, and that then 

 on falling thi^ougli a cloud, which is itself constructed of watery vesi- 

 cles, at a temperature below freezing, the kernel is concentrically cov- 

 ered with ice, which at first is crystallized, and by its further growth 

 assumes its regular crystalline forms. A rotation of the hail storm 

 about any one axis will give it a symmetrical form. {Z. 0. G. M.^ XV, 

 1880, p. 133.) 



Dr. Hildebrandsson has endeavored to introduce further intelligent 

 conformity among the observers of clouds, and to better illustrate the 

 classification adopted by himself at Upsala has published a volume of 

 photographs of clouds in which scA'en plates are devoted to cirro- 

 stratus and nimbus, and five are devoted to ciiro- cumulus and strato- 

 cumulus, and four to the cumulus and cumulo-stratus. The photo- 

 graphs are by Osti. In general Hildebrandsson adheres to Howard's 

 terminology. (Z. 0. G. M., Vol. XV, p. 242.) 



Haun has investigated the annual period of rainfall in Austria- 

 Hungary, making use of all observations available up to the year 1878. 

 These observations refer to 181 stations, of which 146 furnished series 

 of ten years or more in length. The principal question and most im- 

 portant one to be investigated was, how far the annual distribution of 

 rain at the neighboring stations agreed or differed among themselves. 

 To this end each monthly rainfall was converted into a percentage of the 

 annual rainfall, and the results arranged into thirty-four groui)s, repre- 

 senting as many localities. Among the generalizations thus brought to 

 light is the fact that on either side of the Donau there exists a decided 

 tendency to a double maximum of the rainfall in June and August 

 respectively, while in other portions of the empire the maximum oc- 

 curs either in June or October. [Z. 0. G. M., Vol. XV, 1880, p. 249.) 



Mr. Dines has made some observations in regard to the size of the 

 water particles or drops in dense fogs. The magnitude of these particles 

 is not uniform even in the same fog, but varies between 0.000G2 inch and 

 0.005 inch ; but these larger particles are only observed in very dense 

 fog and at a time when the rain itself is falling. {Z. 0. G. If., Vol. XV, 

 1880, p. 375.) 



Koppen and Sprung have investigated the distribution of rain over 

 the Atlantic Ocean, as it results from the observations made on the ves- 

 sels of the German marine during the years 1868 to 1872, and recorded 

 in 178 journals selected from a large mass of records. They state that 

 at all seasons of the year we find on the Atlantic Ocean three large 

 regions especially rich in rainfall, viz, the equatorial and the two extra- 

 tropical, and between these lie two regions of scanty rainfall, which are 

 the two zones of trade winds, but in these latter the deficiency of rain 

 is only a relative quantity, and it is only in special regions, especially 

 in the eastern half of the ocean, that these become regions of no rain- 

 fall. In general, even in the trade- wind regions, from 20 to 30 per cent, 

 of the days have showers of rain, and the frequency of the rain is, there- 



