Evening star. [volume] (Washington, D.C.) 1854-1972, 1930-01-07
ANSWERS TO QUESTIONS
BY FREDERIC ]. HASKIN.

| greenhouses? What vegetable crops
| lead in this respectful. D. G.
A. Greenhouse cucumbers are one
Of the three most important vegetable
| crops grown in forcing houses. Lettuce,
cucumbers and tomatoes make up the
bulk of the vegetable forcing crop OF
| the United States.
Q. Does balsa wood absorb much
| moisture?-S. r.
,. 1t is very absorbent, and when
iced under water light pieces may
absorb as high as 500 to 900 per cent
moisture. Its life is said to be very short
under ordinary conditions unless treat
ed with preservative.
Q. What is the gem called hidden
! ite?-E. H.
A. Hiddenite is a green, transparent
variety of spodumene used as a gem
stone. A well marked prismatic cleav-
| age renders the mineral rather difficult
to cut. Its color passes from an en-
erald green to greenish yellow and Is
often unevenly distributed through the
stone, which shows much fire when
properly cut. iddenite was originally
found as loose crystals in the soil, but
was afterward worked in q vein stone
where 1t occurred in association with
| quartz, garnet and other minerals.
@. How is helium produced?-R. H.
A. The isolation of helium In the
pure state is a matter of some diff
Guilty. To begin with, some mineral
uraninite, Is finely powdered and heat
ed with dilute sulphuric acid, the air
being excluded and the expelled gas
being collected over mercury. The gas
mostly helium, but containing also
nitrogen and other atmospheric con-
| sSituentS-tS next transferred into an
evacuated vessel partly filled with a
mass Of charcoal and cooled from the
outside with liquid air; the charcoal
gradually absorbs everything except the
helium and part of the neon, and If
the process is repeated several times,
nothing but pure helium remains be-
hind unabsorbed.
Q. How many States were there in
the Union at the close of the War Of
1812?-F. j. j.
A. There were 10 States In the
Union at the close of the war which
ended late in December, 1914.
Q. How did traffic lights and towers
originate?-K. E.
A. A test of the traffic towers advo-
Gated by DR.. j. F. Harris took place at
Times Square, New York City, Janu-
airy 5, 1922. Towers were installed
February Of the same year. The
use Of lights in traffic signaling I'M
doubleday grew out Of railroad practice.
Their use seemed to arrive more or less
simultaneously In the larger. cities of
the country. They were first used In
the form of lanterns to make visible
at night the indications of officer
operated semaphores. Later both
| officers and lights were raised in towers
| for the purpose Of making the indica-
tons more visible to traffic and to give
the officers better view Of traffic con-
ditions and the activities of officers at
adjacent intersections. Detroit had one
of the first Of these tower systems. The
advantages of officers at adjacent inter-
| sections working together led to the
development of tnterconnected, me-
chemically timed signals and the sub
| sequent development of the elaborate
technical methods which are in general
use at the present time.
Q. How many absolute monarchies
are there in existence today?-S. I.
A. The absolute, monarchies of the
world today are Abyssinia, Nepal, Siam
and Afghanistan.