POPULAR MISCELLANY. 



4 2 3 



ing of the sun's fiery matter. None of these 

 theories is fully satisfactory. The hypothe- 

 sis of clouds of smoke hardly agrees with 

 the immensely high temperature we have to 

 ascribe to every part of the sun's surface, 

 and the supposition of a dross would re- 

 quire a greater degree of cooling than could 

 possibly take place there. Ilerr Edmund 

 von Ludwighausen Wolff has advanced the 

 theory in " Kosmos " that the spots, instead 

 of being cooler, represent parts of the sun 

 that are vastly hotter than the rest of its 

 body ; that is, that they are regions in which 

 all the heat-movements have reached the in- 

 tensity of the ultra-violet and invisible rays ; 

 consequently, they appear dark. Herr Wolff 

 remarks that Secchi's observation that the 

 spots gave out not less but more heat than 

 the rest of the sun's surface, and Fraun- 

 hofer's that the forces that produce the 

 spectrum-lines appear to be more active in 

 the spots, and the fact that flashes of light 

 are frequently seen to spring up from the 

 midst of them, are contradictory to all pre- 

 viously received theories, but agree fully 

 with that which he proposes, and are clearly 

 explainable by it. 



The Laws of Rain-fall. Professor E. 



Loomis has prepared, in aid of his studies of 

 the laws affecting the amount of rain-fall at 

 different places, a graduated table of the 

 average annual rain-fall at more than seven 

 hundred points. Of two hundred and four 

 stations at which the mean exceeds seventy- 

 five inches (rising from this amount to 492*- 

 45 inches at Cherapunji, Assam), some are 

 elevated more than two thousand feet above 

 the sea, and nearly all are within one or two 

 hundred miles of elevated mountains. Rain 

 chiefly occurs when the wind from the ocean 

 is blowing toward the mountains, and the 

 extraordinary rain-fall at most of them is 

 probably due to the influence of the mount- 

 ains, by which the wind is deflected upward 

 to such height that a considerable part of 

 the contained vapor is condensed by the 

 cold of elevation. The cases in which the 

 rain-fall is excessively deficient are, on the 

 other hand, those of places in which nothing 

 exists that may cause an upward current of 

 air. Another cause of deficient rain-fall, 

 frequently exemplified,>is the descent of a 

 current of air which has been forced up to 



a great height and suffered condensation of 

 its vapor, after it has crossed the mountain, 

 by the influence of which it has been raised, 

 when its temperature rises and it becomes 

 dry. Such effects are produced by the 

 Rocky Mountains on the plains east of them 

 and by the Himalayas on the Desert of 

 Gobi ; and the operation of these two 

 causes will assist in explaining most of the 

 rainless districts of the globe. Other in- 

 fluences modifying the amount of rain-fall 

 are, the meeting of the northeast and south- 

 east trade-winds, which results in a great 

 rain-belt surrounding the globe ; the irreg- 

 ular barometric depressions of the middle 

 latitudes, indicating frequent storms ; prox- 

 imity to the ocean, especially when the prev- 

 alent wind comes from the sea ; and the 

 projection of capes and headlands into the 

 ocean, which contribute to frequent rains. 

 Uniformity in the direction of the winds 

 throughout the year, such as prevails in 

 the trade-wind regions, obstruction of the 

 free movement of surface-winds by mount- 

 ains, remoteness from the ocean measured 

 in the direction from which the prevalent 

 wind proceeds, and high latitude, tend to 

 produce a dry climate. These principles do 

 not seem to be fully borne out by the phe- 

 nomena of rain on either side of the Alle- 

 ghany Mountains, but we have not yet sys- 

 tematic enough or careful enough observa- 

 tions to enable us to determine what is their 

 real influence. Mount Washington, in New 

 Hampshire, exerts a marked influence. The 

 mean annual precipitation there is seventy- 

 seven inches, while in the surrounding dis- 

 tricts it is only forty inches. 



Improved Sanitary Condition of Lon- 

 don, The report of the English Registrar- 

 General for 1880 completes the fourth dec- 

 ade of reports since the weekly return of 

 that officer was first published. It shows 

 that the death-rate in London for the year 

 (taking the population of the metropolis as 

 given by the last census) was not more than 

 21*5 per thousand inhabitants, than which 

 a lower death-rate has been returned in only 

 three of the last forty years. The decade 

 closing with 1880 was one of lower mor- 

 tality in London than any of the three de- 

 cennial periods for which trustworthy sta- 

 tistics are available, the rate having been 



