320 SCIENTIFIC RECORD FOR 1884. 



novel in hydro- mechanics and also extremely suggestive to the students 

 of atmospheric motions and cloud formation. {Nature, xxx, p. 88.) 



214. G. H. Darwin communicates to the lloyal Society of London an 

 extensive paper upon the formation of ripple marks in sand. This is 

 not only a very suggestive phenomenon in hydrodynamics, but, as the 

 author suggests, may possibly have a bearing on the mode of formation 

 of the " mackerel sky " and other forms of cirrus. [As regards the 

 formation of the long cirrus threads, we should prefer the explanation 

 by Eev. Clement Ley to that given by Darwin.] [Nature, xxix, p. ICl.) 



215. Prof. J. W. Mallet has made an extensive compilation of data 

 relating to the analysis of drinking-water and rain-water, which is pub- 

 lished as a report to the United States National Board of Health. 



216. A. von Danckelman, of Leipsic, has investigated the observa- 

 tions of precipitation made in Saxony, 1864 to 1881. Among his results 

 we quote the following : 



The maxim am probability of rain (0.C3) falls in the decade March 2 

 to 11 ; also June 30 to July 9, and November 27 to December G. The 

 minimum probability (0.40) occurs in the decades September 28 to Octo- 

 ber 7, and May 1 1 to 20. 



The relative number of days of snow and days of rain are in the 

 winter 50, spring 22, and autumn 13 per cent. The number of days free 

 from snow varies from 204 at one station to 157 at different stations. 

 {Z. 0. G. 31., XVIII, p. 302.) 



217. Dr. J. Miiller gives a very complete collection of the results of 

 observations of rain and snow in Switzerland, some of the longer series 

 representing sixty years of observations. The region of greatest sum- 

 mer rain is on the northern side of the Alps ; in this region the winter 

 and autumn rains increase from east to west, but the summer rains di- 

 minish ; the region of minimum rainfall embraces the Canton of Tessiu. 

 {Z. 0. G. j\l., XIX, p. 343.) 



218. Professor Topfer has published an elaborate investigation into 

 the rainfall of Germany, which is printed by the association at Gorlitz. 

 He finds that the upper stations have a much more uniform distribution 

 of rain through the year. The heaviest rainfall in stations of long series 

 occurred at Klausthal and Freudenstadt and the summit of the Brocken ; 

 the least occurred at Wustrow and Muhlhausen. {I). M. Z., i, j). 258.) 



219. E. Millosevich has published an exhaustive monograph on the 

 distribution of rainfall in Italy. Italy possesses many stations having 

 very long series of observations on rainfall; for instance, Padua, 155 

 years; Milan, 110; Verona, 81; Palermo, 74; Pavia, 63; Naples, 59; 

 Eome, 55 ; &c. These, therefore, give the author opportunity to study 

 not only the geographical but also the chronological distribution and 

 periodicity. In a land of such varied topography the variations of 

 climate are so great that it would be impossible in the present summary 

 to give any idea of the richness of the storehouse of information con- 

 tained in this volume. {Z. 0. G. M., xix, p. 49.) 



