28 TRANSPIRATION IN A DESERT PERENNIAL. 
The atmometers used were No. 245, white, and a brown* one of the same 
type, which was not numbered in the series, but is called No. 10 for conven- 
ience. The white atmometer was accidentally destroyed before restand- 
ardization was made and therefore the readings for it are not comparable 
in actual amount to the brown cup nor to any other readings in the other 
experiments. The equivalent for the brown cup was 178 sq. cm. of free 
ae oe 
fr .06 ee E 
eee 
05 — 
04 Poise 
oe 
03 Be 
a 
02 x 
s 
4 
01 ee 
23 v v " " u " ut Nod 
= v v " " n i" u No. 2 
oa v Vv “ a u " t No 3 
~~ vou " " tt u u No. 4 
Fia. 14.—Graphs for relative transpiration of four potted plants, 
brown atmometer being used for evaporation rate. Exp. IX. 
water surface. The situation was in the open with exposure tosunand wind. 
A heavy wind threw sand on the pots and thus spoiled the readings after 
1538"p.m. The atmometer readings for 24 47™ p.m. show that the maxi- 
mum evaporation for the day was between 12 noon and 1530™p.m. Air 
movement was confined to a very gentle breeze during the period covering 
the readings. 
*Livingston, B. E., A radio-atmometer for measuring light intensities. Plant World, 
XIv, pp. 96-99, 1911. 
