30 EXPERIMENT STATION RECORD. 



degrees above tlie normal. The period from May to July was exces- 

 sively wet, from August to October excessively dry, the rainfall being 

 92 mm. in June and in September. In fact tbere was no rainfall 

 from Angust 14 to the last of September. The report on observations 

 on the temperature and water of the soil are noted (p. 36). Observa- 

 tions with different forms of actinometers are reported. Eeducing tlie 

 results obtained with the distillation actinometer by means of Hou- 

 daille's formula, it was found that the number of calories registered 

 during 1895 was 114,411. A general correspondence between the tem- 

 perature of the air, hours of sunshine, and calories is traced in a 

 diagram. 



An account is given of observations on the period of growth, sums 

 of temperature, and hours of sunshine, and calories of heat received 

 during different parts of the period of growtli are reported for sweet 

 corn seeded at 3 different dates and at different distances. 



The influence of color on the quantity of heat absorbed was tested 

 by means of thermometers with cylindrical and spherical bulbs in 

 black, white, and different-colored wooden cases, and by observing the 

 heat transmitted by red, green, blue, and white glass. The heat 

 absorbed increased with the depth of color, the order being on August 

 22, black 07° C, indigo 06.8°, violet 06.5°, blue 6G.3o, green 05.5°, red 

 60°, orange 59.5°, white (dull) 58°, and white (shiny) 50". The amount 

 of heat transmitted by the different-colored glass decreased as the 

 extreme right of the spectrum was approached, the order being white, 

 red, green, blue. 



A soil artificially blackened showed a temperature 10° higher at a 

 depth of 0.5 meter than a light soil under the same conditions. Soils, 

 therefore, store up heat somewhat in proportion to their depth of color, 

 and the same may apply to i)lants. The green blade of corn, for 

 example, when exposed to the sun may attain a higher temperature 

 than an uncolored thermometer placed under the same conditions. 



Chapters are given on the action of different rays of the solar spec- 

 trum on vegetation, the internal temperature of trees, the transpira- 

 tion of plants, the action of electricity on plants, and various other 

 experiments on plants. 



The determination of the relative quantities of aqueous vapor 

 in the atmosphere by means of the absorption lines of the spec- 

 trum, L. 1], Jewell ( U. S. Dept. Agr., Weather Bureau Bid. ](!, pp. 12., 

 fig. 1). — This is a report of observations on "the rain-band" during 

 the period from January IG, 1892, to January 31, 1893. 



"The method of observation wsed was to estimate the intensity of a water- vapor 

 line ill terms of the solar line most nearly equal to it in intensity, and in close enongh 

 proximity to render the comparison easy and sufliciently exact. One observation 

 generally included sev'eral comparisons. . . „ 



"Having selected a series of comparison lines, it became necessary to determine 

 the relative intensities of both the solar and the water- vapor lines used in the com- 

 parisons, in order that the observations might be available for actual measurements 



