The Hawaiian gazette., 1896-07-03

the land, as at Eva, then the moisture
is pumped out of the soil quickly, and
even at the end of two or three weeks
the water left in the ground is not
enough to keep the cane in growth.
Eva has to pump up the underwater
brought from the mountains by strata
drainage to keep the crop going. At
the same time it is observed that the
underground Of the lower lands is
| abundantly porous to take down all
water that is not absorbed by the sur
face soil. Many examples Of this are
seen on the windward side of the Is
land, and notably at Waimanalo, where
in many places the streams coming
down the rock sides, as soon as they
touch the land, disappear without any
surface flow. Where great number of
cascades converge to one low point, a
stream is formed.
All these considerations, however
tell US that we must go to the mount
aims, not only to estimate the rainfall
but also to form any approximate ideas
of what becomes of it. The average of
a number of rain gauges gives the rain
fall near the sea level at about 35
inches. Readings that have been made
for Is years at level of 900 feet, and
2% miles up, show an annual rainfall
of 116 inches. The rainfall, for the same
level, differs, however, with the locali-
ty. Nuuanu Valley has a greater rainfall
at 1000 feet than is found in other
places. These facts have to be borne
in mind in the effort to approximate av-
erages. Nevertheless, as a rule, the
rainfall rises with the altitude, and at
highest levels it, of a necessity lex
planned by several considerations,
reaches more than double the average
for the Island. Then there is to be con-
sidered the extent in length, as well as
in breadth, of the windward attitudes
of the Island, not to mention the Wal
amaze elevations; from Makapuu Point
to the drop of the mountain range at
Kahuku the length is about twice that
OF the plain from Pearl City to Waialua
That the great body of the rain falls
upon the mountains, is a question that
does not need discussion, and we may
consider what becomes of the water?
Here are to be chiefly kept in view the
conditions which control evaporation,
and Transportation of water by plants;
because the great body of moisture not
given back to the air must chiefly find
its way by strata drainage to lower
levels, the surface discharge being only
a small part of that total, which is
shown by the fact that it is only after
occasional great rains that the most
of the streams flow, whilst rain falls
upon the mountains a majority of days
in the year.
Evaporation and Transportation of wa
ter by trees and plants, are chiefly con-
trolled by light, temperature, and the
humidity of the air Deherain has
shown that Transportation is ten times
greater in full sunlight than in dark
ness, and during dull, cloudy days
without rain and with the same air tenn
perature, the Transportation is one-half
less than under the action of direct
solar rays" The zone of high rainfall
on the mountains has lower temper
ature, the latter decreasing with the
increase of altitude, the low tempera-
III { 10 l4AC III 81 Oclu5C VI p1
The lower temperature not only causes
the precipitation of rain, it also causes
veil of clouds, which is never quite
absent, and during the greater part of
most days in the year, overspreads the
rain zone, thus reducing the possible
Transportation by vast measure.
This cloudiness indicates high hui
Nudity of the air, and concerning the
action of humidity on Transportation we
have absolute data: Risler found that
plants growing in soil containing only
10 per cent. of water, with an air tenn
perature of 80 degrees, wilted down di-
rectly when the humidity in the air was
only 55 degrees. But with a humidity
of rs degrees the plants stood up fresh,
showing that the greater moisture in
the air stopped largely the loss of water
from the plants. Evaporation is pro-
portional to the temperature and the
humidity of the air. Then, with the
lower temperature of the mountain at
titude and the air so super saturated
with moisture that it is most frequently
raining, it is seen that during a great
poAb VI bAC IAluC luC COAQcAodllOn nOl
only balances the evaporation, during
which time no moisture is being lost,
but the GOODNESS of the mountains takes
the water from the winds as they are
passing over, the great body of which
must find its way through the rock
crevices to the lower strata. Direct
evaporation from the earth even ag-
gravated by the high winds, is reduced
to minimum by reason of the dense
foliage which covers the ground. Dur
ing the portion of days when the sun
is unclouded it must be borne in mind,
however, that Transportation is very rap
i'd. The ground is saturated with mois-
ture, a condition that allows all the
water to pass direct to the lower strata
whilst rain is falling, but when the air
is clear it allows evaporation to pro-
coed more rapidly, which has been
proved by our own experiments. And
when trees and plants are in active
Transportation they dissipate huge guam
titles of water Haberlandt has shown
that an acre of oats during its growth
drew from the ground $40 tons of wa
ter; of wheat. 4S9 tons; of rye, 334
tons. Further, Hohnel found, in ex-
periments with very young trees, dur
ing half year, from June to Novem-
| Der that for each mound of dry weight