536 



METEOROLOGY. (RAINFALL, ELECTRICITY.) 



The table calls for some explanation. In the 

 south of Europe snowfalls are regular in all the 

 elevated parts of the interior ; occasional snows 

 fall in all Europe, in Tripoli, Algeria, Upper and 

 Lower Egypt, and all Syria and Mesopotamia. 

 In Africa snow falls regularly on the Atlas 

 range, as well as on the snow-capped mountains 

 of the equator and the mountains of the Cape, 

 but only exceptionally on the southern coasts 

 and in the interior of the Cape Colony and the 

 Transvaal Republic. The equatorial limit in 

 Asia corresponds with the high zones.. Shang- 

 hai, in a region of regular falls, presents an ex- 

 ception in having them only occasionally. The 

 phenomena on eastern coasts are different from 

 those on western. In Australia the southeastern 

 districts have occasional snows, and it is only in 

 the highest and most mountainous regions that 

 snow falls regularly. Among the high mount- 

 ains of South America the limit of snows ap- 

 proaches the equator. The eastern plains to the 

 tropic have occasional falls. The equatorial line 

 of snow everywhere upon the continent comes 

 nearer to the torrid zone than to the sea. 



Dr. Hellmann has shown that in Spain profound 

 differences in social and agricultural conditions 

 have developed themselves between the districts 

 where the rainfall is great and those where it is 

 small differences which control the character 

 and mode of life of the inhabitants. All the 

 stations in common showed a minimal rainfall in 

 the summer in July and August. The curve 

 of maximal rainfall shows three typical forms 

 and three transitional forms. One set of sta- 

 tions shows a maximum in winter, another set 

 has its maximum in the spring, and the third 

 shows it in the autumn, and between these three 

 a graduated transition is observed. The quo- 



,. , maximum . 



tient : increases rapidly on going south. 



minimum 



The rain storms are rarely continuous : they 

 occur chiefly in the morning, and are followed 

 by sunshine. Snow rarely falls. 



Prof. T. Russell, of the Signal Office, Wash- 

 ington, estimates the entire annual rainfall of 

 the United States at about 1,400 cubic miles. 

 This water would fill a difoh half a mile deep 

 and a mile wide, extending from New York to 

 San Francisco. The average entire rainfall per 

 second would fill a cubical box whose edges 

 would measure 187 feet. 



The mean annual rainfall in Missouri, accord- 

 ing to Prof. Nipher's collation of observations 

 for ten years, varies from 44 inches on the south- 



ern, to 32 inches on the northern border. The 

 average amount of rainfall is 195,800 cubic feet 

 per second, while the average discharge, of the 

 Missouri river opposite St. Louis is 190,800 cubic 

 feet per second ; hence, if all the rainfall of Mis- 

 souri reached the rivers it would cause a larger 

 outflow than is actually afforded by the entire 

 drainage basin of the Mississippi, including the 

 valley of the Missouri river above St. Louis. 

 This drainage area contains 733,120 square miles, 

 while the State of Missouri contains 69,415 square 

 miles, or less than a tenth as much. 



A " black rain " was noticed in a part of 

 Worcestershire, England, on the first day of 

 July. In road ruts where rain water had collect- 

 ed, a considerable film of black sediment re- 

 mained the day after the storm. The day had 

 been remarkable for a dense canopy of shifting 

 masses of dark-colored nimbus clouds. Rain 

 storms had been prevalent, with low temperatures 

 and weather more like that of November than of 

 July. 



Electricity. A paper read by MM. Elster 

 and Geitl before the Vienna Academy gives the 

 results of a year and a half's observation of atmos- 

 pheric electricity on the north side of the Wol- 

 fenbtittel. A marked difference was found be- 

 tween the phenomena of spring, summer, and 

 autumn on one side, and of winter on the other. 

 In the former seasons the daily variation of the 

 fall of potential showed a distinct maximum be- 

 tween 8 and 9 A. M., as Exner found at St. Gil- 

 gen, and a distinct minimum between 5 and (> 

 p. M., whereas Exner found a maximum about 6. 

 The variations in winter are irregular; but a 

 weak minimum occurs about 11 A. M., and a more 

 decided maximum about 7 P. M. The authors be- 

 lieve that other factors than humidity, with 

 which Exner seeks to explain the variations, are 

 concerned in the case. When the temperature 

 falls below zero, a cold mist being then gen- 

 erally present, a rather sharp rise in the values 

 often occurs, consequent upon the less reaction 

 of the aqueous vapor. Rainfall in a neighboring 

 region lowers the fall of potential both in winter 

 and summer, and a disturbance of the normal 

 course will announce a coming change in places 

 still unclouded. 



Some interesting observations were made by 

 M. Gr. de Rocquigny Adanson of two Lombardy 

 poplar trees at Baleine, France, which were 

 struck by lightning on Sept. 20.. The trees 

 were about a kilometre apart, with 130 other 

 trees Lombardy and Virginia poplars be- 

 tween them, none of which were struck. The 

 lightning entered both trees about half-way up 

 to their tops, the upper parts not having been 

 marked by it. The course described by it was 

 an elongated helix, five eighths of a spire being 

 traced in one case, and half of a spire in the 

 other; the direction of both spirals was inverse 

 to that marked by the hands of a watch. Of 

 somewhat similar import to these were the ob- 

 servations by M. F. Terby of two trees that were 

 struck by lightning between Louvain and Fisle- 

 mont, in Belgium. Two poplars were in this case 

 chosen out from a row of elms, and the light- 

 ning entered them about the middle, without 

 their upper parts being affected. 



Phenomena of globular lightning were wit- 

 nessed, at a date not given, by a party of geo- 



