range of altitude and of r 

 ind 34. It h 



tablish a 



loped by n 



t the garden « 



of the 



it for : 



s Nos. 28, 30 

 to be able to 



ing evaporation. 

 On the sixth of June, 1907, the evaporimeters were installed 

 it three stations within the Garden. These instruments consist 

 >f a pint fruit jar, tightly corked with a cork stopper soaked in 

 jaraffine. Through the stopper a glass tube extends from the 

 jottom of the jar up and through a second cork, which tightly 

 :loses the opening into a porous clay thimble. The glass tube 

 :xtends to the top of the thimble. For further protection against 



the 



: of v 





of cloth 



was fitted tightly around the glas 

 over the top of the fruit-jar. 



The jar was filled with distilled water up to a zero mark, and 

 the pogDus thimble and the glass tube were also filled with dis- 

 tilled water. Each evaporimeter was sunk into the ground to the 

 level of the top of the fruit-jar. As evaporation took place from 

 the surface of the thimble the water rose from the jar up through 

 the glass tube, thus keeping the thimble full and lowering the 

 surface of the water in the jar. The rate of evaporation varied 

 with the relative humidity of the surrounding air, and the amount 

 red by carefully poi 





a gradu; 



1 the 



11 the 



ark. The ; 



mplish 



Station 1 (evaporimeter No. 28) was west of the propagating 

 houses on a dry, rocky knoll, covered with only a thin layer (one to 

 two feet) of soil, and well drained. The instrument was shaded 

 on all sides by tall saplings of red cedar and Ailanthus, and nu- 



difolia, and ferns. The surface of the grounc 

 twigs and dead leaves. Station 2 (evaporim 

 about fifty feet south of the stable, near the ea; 

 garden. The ground is low, poorly drained, i 



r No. 30) was 

 n border of the 

 marshy during 



