METEOROLOGY. 



365 



which thunder is heard, shows that the islt.nd of Corfu belongs to a re- 

 gion in which electric discharges are more frequent than in any other 

 part of Europe. {Z. 0. G. M , xix, p. 123.) 



344. P. von Salis, telegraph inspector, has collected a mass of statis- 

 tics relative to lightning on telegraph lines, and at other stations dur- 

 ing the past thirty years in three cantons of Switzerland. He finds— 



1. That in a remarkable way, with extraordinarily few exceptions, 

 and even then only where we may safely infer the presence of a great 

 quantity of water in the ground, all and every lightning discharge 

 occurs upon telegraph lines in the immediate neighborhood of a small 

 or large brook or river; further, these also occurred in the case of the 

 telegraph poles established for conveying submarine lines on the shore 

 of the lakes and never occurred elsewhere. 



2. That the lightning for the past thirty years has occurred more fre- 

 quently on lines in the lowlands and valleys inclosed between high 

 mountains than on the highest Alpine passes. This latter conclusion 

 is borne out by the following table: 



Altitude of the line. 



M. 

 TJnder 500 

 1,000 

 1,500 

 2,000 

 2,500 



Length of the line. 



Kilometers. 

 226 

 263 

 156 

 196 

 65 



Number of 

 liahlniug strokes. 



{Z. 0. G. M., XVIII, p. 384.) 



345. Prof. W. von Bezold has discussed the cases of destructive light- 

 ning in Bavaria during the years 1833 to 1882; this work is a continu- 

 ation of a lesser work nndertaken some tifteen years ago Among his 

 results we note that the frequency of destructive lightning when re- 

 duced to uniformity in the matter of buildings has almost steadily in- 

 creased in forty years to more than three times its previous frequency, a 

 remarkable phenomenon but apparently well established. As the prin- 

 cipal object of his investigation, von Bezold presents on a chart the 

 geographical distribution of lightning strokes for the year. (i>. M. Z., 



I, p. 339.) , . , 



346 Dr. Kavser exhibited to the Berlin branch of the Meteorological 

 Society photographs of flashes of lightning, one of which showed four 

 parallel flashes from top to bottom, which must have occurred simulta- 

 neously or in very close succession; his opinion was that a double dis- 

 charge going ami coming had occurred, the course of which (through 

 air of least resistance) had of course been displaced by a strong wind. 

 The amount of the displacement could be observed on the photographs 

 whence he calculated the time between the first and second discharge. 

 {Mature, xxx, p. G52.j 



