618 EXPERIMENT STATION RECORD. 



Texas wliicli, liowever, occurs in winter, and is due to cold air blowing 

 down and out of a hi^uh area in the inteiior. — h. a. hazkn. 



Meteorological observations considered with special reference 

 to infliience on vegetation, T. Sciireijjer {U. IS. l)ep. Agr., Weather 

 Bureau Bui. 11, pt. 2, Ixpt. Inter nat. ]\[efeorolof/. Congress, 1893, pt. 2, 2)p. 

 395-404). — This article records in part -the results of efforts "to deter- 

 mine liow much of lieat, water, and suusliiue is required by different 

 ])lants, and liow these influential factors are to be distributed during 

 the various phases of plant life." The nature and the difliculty of tlie 

 investigations necessary to attain this object are briefly discussed. 

 The desirability of "s])ecial endeavor to devise methods of repre- 

 senting large series of figures by mathematical expressions" is urged, 

 and the attempt is made "to represent the results of a system of sta- 

 tions as functions of their position on our globe." 



"If y denotes any given meteorological element, eitlier the 8imj)le values of simul- 

 taneous observations, or the means of the observations for any given periofl, and 

 -ipXli are the corresponding latitude, longitude, and elevation above sea of a i)lace, 

 then y=/(/ii/<A). 



"In the derivation of such formulas two methods can be employed. According to 

 the first we lay down theoretically certain principles and endeavor to clothe them 

 in fornnilas. According to the second, use is made of the serial form, as 



?/ = 2/o-f &/t + cr/. + rfA-t-e/i = +/V'2 + f7^^+. • • 

 endeavoring to determine the values of the coefficients from the observations, and 

 then see how these observations are expressed by the series. 



'• In most cases it will be found that all but the first two terms are negligible. The 

 principal results of observations made from 1864 to 1890 at 15 stations in Saxony, 

 rejiresenting elevations of fi'om 120 to 930 meters have been compiled. All monthly 

 and annual means thus found for periods of 5 and more years were represented 

 according to the equation y = a-\-l)h. This has therefore been named the funda- 

 mental equation and a the fundamental value, and & the coefficient of elevation." 



The mean valnes themselves have already been published. A few of 

 the principal results of the calculations under present consideration are 

 here given : 



" For the general mean temperature we have 



a = 9.290C. ±0.22^; fo=— 0.574^ ± 0.0-15°; // = ±0.43o. 

 "The coefficient of altitude is for each 100 meters; the mean error is represented 

 by /i . . . 



" A repi'esentation of the equation for the diurnal period is obtained from the equa- 

 tions for the temperatures at 2 p. m. <j and for the minimum temperatures tm. 

 "It follows from 



4=12.63—0.6.56 li and <m=5.46— 0.579 li, 

 that U — im^7.17 — 0.077 li, from which it will be seen that the range of oscillation 

 is diminished 0.077° for each 100 meters additional height. 



"For the 6 a. m., 2 ji. m., and 10 p. m. observations the following values were 

 obtained for the 25 years from 1866 to 1890: 



<6=6.82— 0.463 h 

 <2=12. 63 — 0.656 h 

 f,„=8.37— 0.614 /(. 

 " Here we are impressed with the snialluess of the coefficient of altitude for thehour 

 of 6 a. m. It follows that, immediately after the time of the minimum temperature, 

 during the first hours of the rise, tliere must exist a remarkable uniformity in the 

 vertical distribution of temperature. 



