16 EXPERIMENT STATION EECOED. 



I'ainfall at Chemnitz for a iieriocl of 10 years, beginning with 1895, are recorded 

 and the influence of these factors on winter wheat, winter rye, oats, barley, and 

 potatoes is studied. Sunshine and precipitation are taken as the determining 

 climatic factors. As a basis for his calculations the author uses a so-called 

 weather unit, consisting of 20 hours sunshine and 10 mm. precipitation, 

 although within certain limits an excess of one of these factors is allowed 

 to compensate for a deficiency of the other. He divides the growth of the plant 

 into 2 periods, the first extending from the time of planting to the formation 

 of the ears (in case of potatoes to the time of blossoming), and the second 

 extending from the end of the first to the time of ripening. 



The average number of these weather units and the annual yield of each 

 crop for 10 years (1895-1904) were as follows: Winter wheat, 4.3 units, 1,781.7 

 lbs. per acre; winter rye, 39 units, 1,434 lbs. per acre; oats, 33 units, 1,496.36 

 lbs. per acre; barley, 30 units. 1,409.04 lbs. per acre; and potatoes, 37 units, 

 9,548.18 lbs. per acre. 



Similar data are recorded for oats, rye, and turnips, grown at the experiment 

 station at Dresden during 1908-9. 



Report of the consulting meteorologist, J. F. Yoorhees ( Tennessee Sta. Rpt. 

 J909, j)p. 108-112, charts 2). — This report reviews brietly some of the more sig- 

 nificant data given in Bulletin 87 of the station (E. S. R., 23, p. 14), calling 

 attention particularly to the typical rainfall distribution in Tennessee and the 

 relation between July rainfall and the corn crop. 



It is shown that while conditions are otherwise very favorable to this crop, 

 it is often reduced by dry weather in July. It is pointed out that this unfavor- 

 able condition may be overcome to a considerable extent by tillage and the use 

 of green and stable manures to conserve the moisture. 



Bulletin of the Mount Weather Observatory (U. S. Dept. Affi:, Bui. Mount 

 Weather Observ., 3 {1910), pt. 2, pp. 69-126, pis. 2, fig. i).— This number con- 

 tains the concluding part of an article on Solar Radiation, Atmospheric Absorp- 

 tion, and Sky Polarization, at Washington, D. C, by H. H. Kimball, and includes 

 a very complete classified bibliography of the subject. 



Studies on the phenomena of the evaporation of water over lakes and 

 reservoirs, VII, F. H. Bigelow (Jio. Weatlier Rev., 38 {1910), No. 7, pp. 1133- 

 1135). — Summarizing the results of the investigations mainly on Salton Sea 

 thus far reported (E. S. R., 21, p. 115; 23, p. 15) the author states that "it is 

 evident that the research of the Salton Sea campaign, while settling a number 

 of important points in evaporation, has raised a series of difficult questions. 

 The theoretical side of the problem, the application to the thermodynamic 

 theories, has not been attempted, as this would require an exclusive study 

 under laboratory conditions and processes. Practically it seems necessary for 

 engineers to adopt a standard pan and reduce the observed readings to the 

 open water surface. Thus the evaporation from a 4 ft. standard pan, when 

 corrected for temperature and wind and multiplied by the factor 66 per cent 

 is about what observation suggests. If a water thermometer on a small raft in 

 the lake measures So, and a sling psychrometer measures ca through t and ti, 

 and an anemometer placed as near the water as possible is used for the wind 

 velocity, then the coefficient is C=0.138 for 24-hour intervals. For the formula, 

 use the mean values of So, cs, e.i, w, taken at readings made about 6 a. m. and 

 2 p. m., the times of minimum and maximum meteorological conditions. If any 

 reservoir, where the inflow is measured accurately and the rainfall can be 

 fully accounted for, can be observed for some time it may be possible to check 

 further the accuracy of this formula. Since local conditions count so much on 

 the action of an evaporation pan it would not be possible to improve this 

 formula by any small number of observations. The formula can easily be ex- 



