46 TROWBRIDGE: THE THERMOMETRIC MOVEMENTS 
No. 2, the Paulownia. Sixty-five pounds were added to the 
branch, five pounds at a time. This experiment was made both 
at a temperature above freezing, and also at a temperature well 
below freezing. It is seen that the constant of elasticity has 
changed in both cases, and the amount of depression per pound 
has decreased for the branches of both trees at the lower tempera- 
Daily Record OATS eM eh 
: : aoe ae 
: Foo 
t HEIGHT OF BRANCH — 
m5 ++ T A | a 
& if) ff Tree No. ee 
& Pn Gas ae ae oe ed Din & ee 60 
k Temperature F 
34 Z LA et it 
+ :, “ 
2 e | tt dS lug? 
7NECRIALCY Loo 
"4 / \ OSES Roscoe ; pene» : 30° 
a 13 ao 
| |8 
I : 1 
60 FEBRUARY MARCH < oO 
IS 16 17 19 20 21 23 24 26 27 28 2 14 18 12 
Fr Daily record of height of Branch A, Tree No. 3 (sycamore), during 
February, March and April, showing no effects due to variation in air temperatures, 
below freezing, but a rise beginning in February, with a more decided increase in | 
elevation in March and April, especially cccotintn on warm day 
ture. It would therefore appear as if the change in the modulus 
of elasticity of the two branches, due to changes in the temperature, 
had little or nothing to do with the direct temperature effect 
produced in the case of Tree No. 1, the linden, which showed 
large thermometric movements. 
From theory it is to be expected that if there is a ee in the 
modulus of elasticity due to temperature, and if a st'ffen’ng occurs 
at low temperature, the branch would not be as much depressed. 
Such an effect is opposite to the large thermometric movement 
actually observed. In the case of the weighted cold branches 2 
loss in recovery is noted, which is probably temporary, but 
explains certain inconsistencies observed on other observations. 
