The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1899-05-07
BARRELS OF WATER
TRAVELLING UP TREES

1t is not generlly known that many
common plants. such as the poplar,
the arbutilon. the tomato plant, may
be made to compress air in a tube
until d pressure of thirty or more
pounds to the square inch is obtained.
1t is not generally known, further
more, that at this time of the year a
common tree might be made to COM
press air enough to run an engine. Yet
these facts, phrased in more technical
language, perhaps, are known to- every
botanist- This capacity of plants for
generating power is the result of what
is known as root pressure, phenome-
non which becomes manifest mostly
at this season of the year. Professor G.
c. Curtis of Columbia college has de-
signed an instrument for measuring
root pressure. He was asked TO explain
the phenomenon and its cause. In the
course of his remarks he said:
Every spring, before the leaves have
come forth on the trees and shrub
berry, every plant, every vegetable
growing thing, in fact, develops a ca
pacity for sending great quantities of
moisture up through the trunks and
branches and out TO the bursting buds
on the ends of the twigs. The guam
tity of the moisture naturally depends
on the size of the plant. Barrels of
denced by the sap in an apple orchard:
bucketsful ascend the saplings, and
smaller quantities climb up the bushes
No one has yet been able to explain
satisfactorily the force which drives it
up. 1t does not rise because of ca
piliary attraction. From lack of
knowledge of any other cause, we call
it root pressure. 1t comprises one Of
the problems which botanists are con-
stantly striving to solve. The most re-
markable part of it all is the tremen-
dous power of this rising column OF
water. Why, we have found it even in
small plants to attain the compara-
lively great pressure of two atmos-
pheres. or nearly thirty pounds to the
square inch. In big trees the accumu-
lated pressure must be immense. No
one has tested a big tree, although L am
thinking of attempting it as soon as
L can get the proper apparatus. We
know something of the power of root
pressure in small plants, from our la
boratory tests. We have cut off a
plant near to the surface of the dirt
in the flower pot. and then attached
| glass tube to the stump. We filled
the glass tube with water and corked
ii. Yet the rising pressure from the
roots was sufficient to force the cork
from the tube. Water is uncompres-
sible, so the cork had to go, but if the
tube had nothing but air in it, and the
cork was secured tightly enough, the
air would have been compressed.
You could make a fountain on this
principle. You should secure an S.
shaped glass tube of small bore This
glass tube should be secured to the
stump of a cutoff abutilon The
joint can be made with a short piece
of rubber tubing (see diagram), bound
with wire. Into the neck of the tube
should be poured some water Some
of the water should be allowed to run
over into the part of the tube attached
TO the plant. This will leave an air
space between the two portions of
water. \ cork with pin point quill
run through it. should be forced tightly
into the open end of the glass tube
The quill should be capped with a