518 



SCIENCE 



[N. S. Vol.. XXVI. No. 668 



open show the least. Corrections for snowfall 

 and for difference in the exposure of the 

 gauges as regards wind, amount to 5.5 per 

 cent.; the observed difference in catch being 

 5.2 per cent. It thus appears that, as has 

 previously been the case when the conditions 

 of forest rainfall have been critically exam- 

 ined, the probability of error is about equal 

 to the apparent difference in the amount of 

 precipitation. 



The second paper (" Wald und Nieder- 

 schlag in Westpreussen und Posen und die 

 Beeinflussung der Eegen und Schneemessung 

 durch den Wind," ibid., 1906, No. 11) is a 

 critical study of the effect of wind on the 

 catch of precipitation, especially snow, in 

 gauges. 



INFLUENCE OF fORESTS UPON WIND VELOCITY 



M. I. St. Murat, the new director of the 

 Meteorological Institute of Eoumania, has 

 made a study of the retarding effect of forests 

 upon wind velocity (Bucharest, 190Y, 4to, pp. 

 33, pis. 3), which appears in the Ann-ales of 

 the Eoumanian Academy, Bucharest. The 

 subject is one which has hitherto received 

 practically no attention, at least so far as 

 quantitative measurements are concerned. 

 The results are as follows: The greatest effect 

 which a forest can have upon the wind con- 

 sists in diminishing the wind velocity to lee- 

 ward of the forest. At 50 meters (164 feet) 

 this decrease in velocity may amount to 3 to 

 12 kilometers (4-7J miles) an hour, which 

 means a reduction of the force of the wind 

 by one degree on the Beaufort scale. This 

 decrease is felt within 100 meters (330 feet) 

 of the forest. After that the velocity in- 

 creases again with increasing distance, and at 

 about 500 meters (1,640 feet) reaches the 

 force noted before the forest was encountered. 



THUNDERSTORMS AND " FALSE CIRRUS " 



Dr. C. Kassner has investigated the ques- 

 tion of the " false cirrus " and of solar haloes 

 (" Gewitterschirm und Sonnenringe," Met. 

 Zeiischr., July, 1907), with the following re- 

 sult: 



1. Solar haloes before and after thunder- 

 storms show that the cirrus veil is an ice 

 cloud. 



2. It is therefore wrong and misleading to 

 call these cirrus clouds " false cirrus." 



3. The cirrus cloud veil precedes the thun- 

 derstorm on the average by as much as four 

 hours, and follows it by about one hour. 

 Hence the average extent is measured by five 

 hours, or, with an average hourly velocity of 

 progression of 25 miles, the distance covered 

 is 125 miles. 



climatology of south AFRICA 



J. R. Sutton, meteorologist of the De Beers 

 Consolidated Mines, Kimberley, has published 

 three more papers dealing with the climate of 

 his district. These are (1) "A Contribution 

 to the Study of Evaporation from Water- 

 surfaces " (Sci. Proc. Boy. Dub. Soc, XI., 

 N. S., No. 13, 1907, 137-178) ; (2) " Variabil- 

 ity of Temperature in South Africa," and 

 (3) " The Diurnal Variation of Barometric 

 Pressure" (Rept. So. Afr. A. A. 8., 1906, 13- 

 48; 135-142). These papers are all worthy 

 of attention on the part of those interested 

 in the general subjects treated, or in the 

 climatology of South Africa in particular. 



the weather bureau 

 An account of the various activities of the 

 Weather Bureau in saving life and property 

 is given in an article by Gilbert H. Grosvenor, 

 entitled " Our Heralds of Storm and Flood," 

 published in the National Geographic Maga- 

 zine for September, 1907. This article, which 

 is fully illustrated, originally appeared in the 

 Century. 



SALT OF MARINE ORIGIN IN THE ATMOSPHERE 



A PAPER entitled " Quelle est I'lmportance 

 du Transport atmospherique de Sel marin ? " 

 by E. Dubois, published in Ciel et Terre, July 

 16, 1907, is worth noting chiefly because of 

 the bibliographical notes which accompany it. 



E. DeC. Ward 



Hakvard Uni^'eksitt 



TEE DISTRIBUTION OF RADIUM IN TEE 

 ROCKS OF TEE 8IMPL0N TUNNEL^ 



The principal classes of material which 



enter into the composition of the massif of the 



'Read before Section C, British Association for 

 the Advancement of Science, Leicester, 1907. 



