Evening star., 1932-10-14
BY DIR. c. G. ABBOT,
Secretary, Smithsonian Institution.

Not only does the gigantic sun keep
the nine planets with their ~ moons
and the thousand planetoid all In or
derly motion, but he furnishes light,
heat, power, the elements Of life ITSELF
Therefore observing solar radiation Is
not merely for astronomical knowledge
but concerns the practical matter OF
crops, health. weather and power supply.
The Smithsonian Institution carries
on two branches Of solar radiation re-
search. For many years it has been
measuring on high desert mountains In
distant lands the daily intensity Of the
suns rays available to warm the earth.
They prove not constant but variable.
The changes though not large. seldom
exceeding per cent, appear to affect
weather and also long range radio
transmission
Regular Variations.
Though at first sight irregular, the
suns variations prove to be made up OF
some half dozen regular periodicities
There is good prospect that through a
knowledge Of these periodicities the
variation OF the sun may be predicted
for many months in advance. Further
more these periodicities appear to be
reflected In the weather.
Unfortunately the connection Is OBJ
scure and apparently subject to inter-
ference, SO that the amplitudes of the
weather responses due to periodic fluc-
tuations in solar radiation differ from
time to time. There is great hope that
these difficulties may be conquered.
If So weather. forecasts Of one or two
years in advance may result.
Laboratories for plant study have
been established In the Smithsonian
basement. AS clouds frequently hide
the sun in Washington, we have pre-
ferred to use electric glow lamps and
arcs as more controllable sources Of the
rays whose influences on plant growth
is examined. The nature of such rays
is identical with sunlight and differs
only as regards intensity, which can
easily be controlled.
The most important chemical reaction
in the world Is that whereby green
plants under the influence of radiation
absorb carbcnic acid gas from the air
and with the addition Of water and
traces Of chemicals collected through
the roots, synthesize starch, cellulose
and all the thousands of plant chemical
products.
Special Devices Invented.
Strange as it seems, the O03 per cent
Of carbonic acid gas in the air fur
nishes all the carbon that makes up
trees. All the coal produced In former
ages CdIlc llOIll lllc all d1SO. 1ldIlIS
will not grow without radiation and
animals, including man, would starve
without plants. Hence all life depends
on the photosynthetic reaction just re-
ferred to.
Every change in temperature. hu-
m dity, carbonic acid and chemical root
food and in the quality and intensity
of radiation supply affects plant growth.
We have therefore invented many spe-
cial devices of great sensitiveness where
by all these factors surrounding plants
may be varied at will.
We are not content to deal with the
simplest plants like the algae, but use
oats, wheat, tomatoes, palms and other
high-class plants In our experiments.
Although established but two years.
already novel results are being published
from our plant growth laboratories
These cover the killing effect of ultra
violet rays; the bending of plants to-
ward the light: the dependence of wheat
growth on intensity of radiation and
abundance of carbonic acid gas; the
transparency of chemicals to radiation
and the optimum conditions for palm
nurseries. Every advance uncovers q
multitude Of practical problems. far be-
yond our financial means to undertake.