METEOROLOGY WATER. 619 



tlie precipitation at the experiment farm from September 1, 1910, to December 

 31, 1012. 



Meteorolog-ical summary for the year 1912, J. F. Wilson (Wyoming Sta. 

 Rpt. 1913, pp. 125-185, figs. 6). — Monthlj' summaries are given of observations 

 at Laramie, Wyo., during 1012 on temperature, pressure, precipitation, hu- 

 midity, sunshine, cloudiness, and wind movement. A record of soil tempera- 

 ture at depths of 3. G, 12, 24, 36, and 72 in. during 1012 is also given. 



The highest temperature was 87° F., August 26; the lowest, —20", February 

 4. Tho total precipitation was 14.70 in. The lowest relative humidity was 11 

 per cent, August 26. The greatest velocity of wind was 72 miles per hour, 

 February 17. 



On the amount of radioactive products in the atmosphere, S. Sat6 (Set. 

 Rpts. T6hoku Imp. Univ., ser. 1, 2 (1913), No. J,, pp. ni-n.',).— in observations 

 at Tohoku University, Japan, by means of a negatively charged wire stretched 

 horiz€Piitally above the ground, the numbers of atoms of radium and thorium 

 emanations per cubic centimeter of air calculated from the results were, re- 

 spectively, Ne=1.5, N'e=1X10-*. 



The soot-and-dust-fall of English towns and cities, J. B. C. Kershaw 

 (8ci. Amer., 110 (1914), No. 3, pp. 63, 6J{, figs. 5).— This is a brief account of 

 the plan proposed by the International Conference on Smoke Abatement for 

 the systematic study of the amount and character of the solid impurities in 

 the atmosphere of large towns and manufacturing centers, and which has been 

 put into effect in England and to a less extent in Germany. Reference is made 

 to methods and apparatus used and to some of the results already obtained in 

 such studies. These indicated that the soot and dust fall varies in certain 

 English centers from 200 to 2,000 tons per square mile per annum. 



The correlation of rainfall, J. Peck and E. C. Snow (Quart. Jour. Roy. Met. 

 Sec. [London], 39 (1913), No. 168, pp. 307-316; abs. in Internat. Inst. Agr. 

 [Rome}, Mo. Bill. Agr. Intel, and Plant Diseases, 4 (1913), No. 12, p. ISJfJf). — 

 From a study of the rainfall at 30 stations in southern and southeastern Eng- 

 land during 1908 to 1911, inclusive, the authors conclude "that while the rela- 

 tive rainfall in December can be predicted from a knowledge of the rainfall 

 in two or three of the previous months with a small degree of probability, that 

 of June and July can not be foretold with the slightest degree of probability." 



Rainfall as a determinant of soil moisture, F. Shreve (Plant World, 17 

 (1914), No. 1, pp. 9-26, figs. S). — This paper presents "a digest of a short 

 record of desert rainfall, interpreted in terms of its possible effect upon soil 

 moisture; gives data showing the annual march of water content at three 

 depths in a retentive clay soil ; indicates the relative potency which different 

 falls of rain were found to have in renewing the store of soil water ; and esti- 

 mates the relative efficiencies of various percentages of soil water for the main- 

 tenance of plant activity by correlating them with the concurrent rates of 

 aerial evaporation." The observations were made at the Desert Laboratory 

 near Tucson, Ariz. 



Summarizing the results, it is stale;! that "the average annual rainfall at 

 the Desert Laboratory is 14.60 in. There are two rainy seasons, that of the 

 summer averages 63 days in length, but yields 54 per cent of the annual rain- 

 fall. The average number of rainy days is 61.5 per annum, on 46.2 of which 

 the rainfall is less than 0.25 in. In six years there were 32 days with more 

 than 0.75 in. of rain, nnd they yielded 46 per cent of the total rainfall of the 

 six years. There have been periods of 140 days without rainfall of sufficient 

 amount (0.15 in.) to affect the soil moisture. 



" The march of soil moisture during the year is closely related to the amounts 

 of the significant falls of rain, and the changes of moisture content are con' 



