OF TREE BRANCHES AT FREEZING TEMPERATURES 41 
The temperature when above 32° has little effect on the 
position of the branch, but whenever the temperature of the air 
passes below the freezing point of water, an immediate bending of 
the branches of the tree takes place. Throughout April and for 
some observations in May, very little change in the position of the 
branch takes place, except depression of the branch due to the 
weight of the leaves in May. Notwithstanding the fact that 
during April and May there was a large variation in temper- 
ature, no movement took place because all the temperatures. 
were above 32° Fahrenheit. In regard to the influence of water 
vapor present in the atmosphere on the movement of the branches, 
it can be seen by the fine line curve in Fics. 4 and 5, representing 
relative humidity, that there is little, if any, effect. This is 
specially evident at points M and WN in both figures, where 
the humidity was high and low respectively with apparently little 
influence on the height of the branch. The curves in Fics. 6 and 7 
Cc 
5 Bett | =~ ae 
Ble ' 
eS ie i \ 
Hourly Record 2 e — 
| ‘Tree No. 1 XN | \ HEIGHT OF BRANCH i] 
| : ia | “ 1 : Branch A 
grit oP 
apt of wa Be ge ee 8 E 
an a me \ 184 57 ri 5a & 
ee M oi i ae ; 4s 5 
Q = “a M 
28 s wa poe : / om Cy 
2 =a a7 
dé ed 
26 8 1 ae 
= N 
a} | , 
e 
aH | Temperature F 
: ATT 
} bee 
‘ DECEMBER 12 -I3 "4 ich C | 
wo —nt10 Wz Po 8 +S 6 7 8 4 10 12PM. 1ONSAM. DEG IS 1112 
Fic. ro. Hourly record of Branches A, B, and C, Tree No. 1 (European 
linden). Temperature on a large scale. Branch C saa ne were made at the 
extremity of a branch. The last reading was taken at 10.45 a.m., the previous 
observation at 12 midnight preceding. 
made with a different branch show effects similar to those observed 
in the case of Branch A. The curves corresponded very closely 
