A SUMMER'S RECORD OF EVAPORATION AND 



PRECIPITATION IN LANCASTER COUNTY, 



PENNSYLVANIA 



CAROLINE RUMBOLD 



Botanical Laboratory, University of Pennsylvania, Philadelphia, Pa. 



In the course of some experimental work in Martic Forge, Lan- 

 caster County, Pennsylvania, records were kept of the rainfall 

 and evaporation during the growing season of 1913. The ex- 

 perimental plots where the work was done were in a chestnut 

 orchard situated on the top of a rocky hill a little over 500 feet 

 above sea-level, about 3 miles north of the Susquehanna River. 



The rainfall was measured by means of a standard rain-gauge, 

 the amount of precipitation being recorded after each rainfall. 

 The evaporation records were made by means of the porous clay 

 cups used by Livingston.^ Six cups were used at a time in the 

 plots, two of them always being installed in the same neighbor- 

 hood. These were swung between the orchard trees by cords so 

 as to be on a level with the center of the leafy crowns. The bot- 

 tles to which the cups are attached were held by nets tied to the 

 cords stretched between the trees. They swung in the wind with 

 the branches, but were able to w^eather safely all the storms, al- 

 though some of them were very severe. The cups were changed 

 and restandardized during the season. 



The evaporation records were measured in cubic centimeters, 

 the rainfall in inches. In order to compare the two sets of rec- 

 ords the cubic centimeters of evaporation are changed to centi- 

 meters of depth. The reductions are based on figures given by Liv- 

 ingston for this purpose.^ For the same purpose of comparison the 

 weekly averages of evaporation and rainfall are given in table 1, 

 which was compiled by Mr. H. L. Van Buren. 



1 Plant World 13: 111, 1910. 



2 Plant World 14: 214. 1911. 



213 



