

KBTBOROL'XiY. 



Mr. K. r. Mossman has found from the examina- 

 tion of the principal meteorological registers and 

 weather records kept in Ixmdon between 1813 and 

 18M for notices of thunderM. Tin*, lightning with- 

 out thunder. f. snow. hail, and gales, that the 

 average number of thunderstorms during tin p.-n- 

 -1 was 9*7 prrnniiuui. tin- maximum .i-curr. 

 July Mini I he minimum in .N-j.:rmlN-r. The aver- 

 age number of fogs was 24 4. ami "of dense fogs" 

 A per annum. Ten-yearly means show that a 

 steady and uninterrupted increase of fog has taken 

 place since 1841. The average number of days 

 with snow was i:i-rt INT annum. The snowiest wm- 

 as that of 1887-*88, with forty-three days of 

 now, while not an instance of snowfall was recorded 

 .terof 18tt-*68. The mean date of th. 

 ftnrt snowfall was Nov. 9. and of the last March 

 30. Hail appears as essentially a spring phanome. 

 noo. reaching a maximum in March an<l April. 

 The minimum wa* in Julv and August. The aver- 

 age number of days with nail was 5*9 per annum. 



Sir John Evans, in the 1> vion. illus- 



trated the extent <>f the local variations in \v. 



in a country so small as Kngland. >>y citing 

 the difference in the amount of rainfall on 'the east 

 and west coasts, whk-h gives the almost absurd ratio 

 U>& 



The phenomenon of rain rushes in thunderstorm- 

 bsj !....'-, , Qsjdsn i bj i'r,,f. Otovelsad AI.I..- m the 

 M Monthly Weather Review." Several plausible ex- 

 planations of it have been put forward from time 

 to time, but have been rejected as erroneous. It i- 

 an open question whether the rain gushes brine 

 about the formation of lightning or are provoked 

 by it. The author makes several suggestions to 

 serve at bases for experiments. 



The question of the influence of forests on rain- 

 fall was reviewed by Prof. II. A. I la/en at the an- 

 nual meeting of the American Forestry Association. 

 Both the historical and the experimental evidence 

 were found to be indecisive so far as they were cited 

 to show that forests promote increase of precipita- 

 tion to any marked degree, " It has been well es- 

 tablished, the author says, " that forests have a 

 most important bearing upon the conservation of 

 rainfall ; that the forest floor permits a seepage of 

 water to the sources of springs, and thus maintains 

 steady flow; that woods hold back the pre- 

 cipitation that falls, especially in the form of snow, 

 thus preventing or ameliorating the effects of dan- 

 ncooj freshets. There is not the slightest doubt of 

 their importance to the welfare of man, but all these 

 facts do not affect the question of their influence 

 upon precipitation. The historical argument. <l. - 

 pending on the contrast between the former fertil- 

 ity and present desolation of certain regions, is met 

 by the answer that there is no evidence of any es- 

 sential change in the absolute quantity of rainfall : 

 but formerly, with lam populations and hiuh civi- 

 lization, the water supply was taken care of in those 

 countries and applied to irrigation, of which the re- 

 main* of immense works are in evidence, while now 

 it is all vastsd. The coincidence of our dense for- 

 ests with the greatest precipitation is probably the 

 result of normal abundance of precipitation. Me- 

 teorologists are agreed that there has been practi- 

 cally oo change in the climate of the world since 

 the earliest mention of uch climate*." The "early 

 and the latu-r mm* are experienced in Palestine 

 now just as they were four thousand years ago. 

 Jordan M overflows all iu banks " to-day in Febru- 

 ary precisely as it did in Joshua's day. Compara- 

 tive gauge measurements of precipitation in forests 

 and the open have afforded no satisfactory results. 

 What is probably the amplest record of such 

 rations, that of Prof. II. A. Blanf.-r.l. in India, 

 showed a possible difference of 2 per cent, in favor 



of the forest. Tin- is M practically inappreciable," 



There is, however, a class of visual observations 

 \* inch seem to show effect upon rainfall of forests. 

 Probably many have seen heavy clouds passing 

 a plain, lint which precipitated onlyasthe\ 

 passed over a forest. Al><> in a hilly region 

 frequent phenomenon thai fog nd low-lying cloud 

 >r a forest, and not over an open plain. 

 also notes \, ry often, in pa-mi; into a forest 

 on a damp day. thai the trees drip moisture, possi- 

 bly condensed* from moisture evaporated from the 

 damp earth underneath. < b-er\at ions of tt, 

 lure, however. <aii not ordinarily lie checked b\ in- 

 strumental means. I, ut show in a general way that 

 the forest tends to conserve vapor and moisture, 

 which in the case of the open field would lie dif- 

 fused into the atmosphere. 



The director of the observatory at Odessa, Rt, 

 has recently published a work on the distribution 

 of rain and thunderstorms over the ^lol.e. in which 

 he assumes that there exists on either side of the 

 equator a /one of electrical activity exactly corre- 

 sponding with the region of greatest ram-. Through- 

 out i 1 the thunderstorms exceed 100 H 

 bevond it. up to 20 or 25 of latitude in lx>th hemi- 

 spheres, thunderstorms are of rarer occur; 

 and in temperate climates they do not much exceed 

 :;<> a year. The most curious" observations in the 

 book relate to countries where thnmlerstorn. 

 ix>t known, and even where it is said n< 

 Such countries are Finland. Iceland, northern Si- 

 beria, eastern Turkestan, Nova X mbla. and all the 

 regions. 



\\ in.K :u hi- investigations respecting wind 



velocity Prof. G. Hellmann has deduced the yearly 

 period for all stations for which he could find a 

 series of ten years' observations and for all i>a 

 the world. His general conclusions are tnat the 

 it.y increases with latitude and decreases from 

 the coast inland; that in the yearly period the 

 maximum in higher latitudes and exposed coasts 

 occurs during the cold season, while in the inl 

 of the continents it occurs between Man i 

 July; that the period of maximum velocity c 

 ally corresponds with that of the stormy s< , 

 that the minimum velocity generally occurs in Au- 

 gust or September at those inland stations that 

 have a spring maximum, while at con 

 which have a winter maximum the minimum takes 

 place in June or July; that the amplitude of the 

 yearly period i- L'leai.r on the coast than inland. 

 but greatest in districts subject to strong period i 

 cal winds and monsoons. 



A summary of the conclusions reached I 



nilian IMessner from a study of the economies 

 of wind as a source of power is given by M. Henry 

 de Varipny in a paper on "Air and Life," published 

 by the Smithsonian Institution. The irregularity 

 of the wind forms the chief objection to placi 

 liance upon it, but much depends upon !<>< 

 There are places and la Qfl where it is 



fairly regular. It seldom fails at the seashore, 

 the trade winds are nearly constant; while in most 

 parts of the globe it becomes mon regular a 

 altitude increases. Hence, upon the whole, a 

 siderable part of the world is well suited for in 

 Rations upon the best methods of deriving j 

 from the winds. The first requisites of a wind- 

 power machine are some sort of a motor dri\ 

 the wind, and an accumulator to stop th* . 

 and yield it at the required moment. Di-n; 

 the old windmill and the wolian wheel as not fully 

 coming np to the mark, M. I'lessncr turns to 

 as affording a possible solution of the problem. 

 "The utilization of the power of the wind 

 writes, "and its transformation into mechanical 

 work are only possible by means of sailing vehicles, 



