Oct. 18, 1915 
Automatic Transpiration Scale 
131 
NOON 
3SO 
300 
eso 
£00 
/so 
/OO 
Af/OH/SHT 
\ ?! <U * 
so 
I. 
^300 
^ 3 S 0 
\eoo 
§/so 
* /OO 
I ^ 
\soo 
$ 
K ?oo 
WHEAT 
yJULr a- 3 ,/ 9 /e 
rate which is momentarily too high. Special provision is made to prevent 
two balls being delivered to the beam in rapid succession, and no record 
is made unless a ball is 
actually delivered to 
the ball container on 
the beam. Four of 
these automatic scales 
have been in use dur¬ 
ing the past four sum¬ 
mers at Akron, Colo., 
and continuous records 
have been secured dur¬ 
ing these periods. The 
results of these meas¬ 
urements will be dis¬ 
cussed in other papers. 
A brief review is also 
given of other forms of 
transpiration bal¬ 
ances, which are di¬ 
vided into two classes: 
Those operating on the 
step-by-step principle, 
which includes the bal¬ 
ances here described, 
and those of the con¬ 
tinuous-record type. 
The first class includes 
balances in which the 
adjustment is secured 
by adding small 
weights (solid or 
liquid) of equal mass 
or by moving a coun¬ 
terpoise in uniform 
steps. In the second 
class the plant is suspended from a spring, or from a variable lever, or 
is mounted (directly or indirectly) on a float. 
WHEAT 
JULY /4-/S, /s/a 
!■ 
ALFALFA 
AUGUST /** /3/V 
600 
soo 
*00 
300 
.300 
/OO 
— 0 
Fig. 18.—Transpiration graphs corresponding to the three records 
given in figure 16, plotted in rectangular coordinates. 
LITERATURE CITED 
* ^ _ a Cited in this 
ANDERSON, A. P. article on page— 
1894. On a new registering balance. In Minn. Bot. Studies, v. 1, pt. 4, p. 
177-180. 117 
Bdackman, V. H. ( and Paine, S. G. 
1914. A recording transpirometer. In Ann. Bot., v. 28, no. 109, p. 109-113, 
1 pi. 119 
