Evening star., 1924-07-13
Shrine of Science National Capital House of Wonder

' ' \JlluOlO
sonality. revealing his spots and 9TH
er mysteries not seen by men until
Galileo's eyes discovered them to a
startled and incredulous world. The
light from this solar image, which
| may be watched on the disk without
injury to the naked eye, then passes
through a narrow slit in the upper
race of the table, descends to an op-
tical grating near the level of the
basement floor, is analyzed in its con-
stftaent parts. and sent back in the
form of a brilliant spectrum.
BY looking down through an eye
piece near the suns image the Wis
itor can see this spectrum, crossed
by the numerous dark lines that
characterize the chemical elements
present in the vaporous atmosphere
OF the SIN itself Hundreds of these
lines are due to iron. If the incredu-
lous visitor wishes TO assure himself
that they really are caused by iron.
he needs but press a button beside
the eyepiece. This starts an electric
arc which instantly vaporizes its iron
poles and permits the resultant lighs
to descend through the same slit sid
by side with the light of the sun
The bright lines of iron in thesa,
coinciding exactly with the dark line,
OF IRON IN the sun. may then be SEGA
at glance. 1t will also be possiIA
with this apparatus, which is not VI.
quite completed, but will soon be -
full operation, to show the widenir,. :.
or splitting of certain lines due to til.
magnetic fields in sunspots, which arr
caused by swarms of electrified par.
ticles whirling in the immense -
texes or tornadoes that constitute /,
spots.
II ANGlNG over the same table is a
heavy pendulum consisting of :.
orass ball suspended by strong wire
from the center of the dome. lam
guidly oscillating back and forth
across the plane. Even as the visitor.
watches for minute the plane seems
to change and the ball seems to be
crossing different lines from those
| when it was first observed. 1t is not
the plane changing at all, but the
earth under it. The building and the
earth itself have squirmed around
| simple proof by means of the Fou-
| cauit demonstration of the earth's
| diurnal rotation.
| One of the smaller exhibition rooms
| adjoining the main auditorium con-
| tains the latest forms of radio ap-
paratus. Wireless telegraphy and
telephony, and long distance teleph-
ony eby wire, with loud-speaking
| tranSmitters, are all demonstrated,
/ but the exhibit does not stop at this
point. Taking advantage of the anna
| teur's interest in the radio, it leads
him by actual experiments and strik-
! ing illustrations to the laboratory of
! Hertz. who detected wireless waves
by their power of producing sparks:
| the earlier demonstration of Henry,
who recorded the waves sent out by
| distant lightning and reproduced
them experimentally; the researches
| of Maxwell, who first conceived of
waves in the ether; the pioneer work
of Faraday, who visualized lines OF
I
| medium of transmission.
| Another iltterrelated exhibit is that
of the vacuum tubes in which the
terrestrial aurora caused by the sun
is initiated. Violet-colored and pull
sating striae of gases at low pressure
are produced by passing through
| them d stream OF electrons, resulting
from an electric discharge. 1t is in
| the same way that the gleam of the
aurora arises from the bombardment
of the earths upper atmosphere by
electrons shot out from the sun. This
aurora can be detected any night in
southern California by means of the
spectroscupe. but when great and ac-
tive sun spots are near the center oil
the sun the number of electrons Is
| enormously increased ard the aurora
is frightened into visibility.
A recording magnetograph demon
strates the spasmodic fluctuations in
the intensity of the earth's magne-
tism which accompanies such cleo
trical storms. Should the visitor then
wish to see the source of these dis
turbanccs he reed only return 10 the
main auditorium and observe tne
spots on the image of the sun, before
described. The spot responsible for
the disturbance will be plainly Vls-
lible, and it's shifting position may De
followed across the disk as the sun
rotates.
THE entire range of the physical
II and biological sciences coverihF
/ the current phenomena of nature. the
apparatus for studying them and the
| means by which fundamental discov-
cries are applied for the public well
fare will 1T some time be displayed in
the National Academy of Science
| building. The exhibit there is to be
an ever-changing one, kept con-
J stantly up to date SO that the public
may go there at any time and actual
! ly watch science in its renewed ef-'
| forts and continued progress towards
| the ideals that are ever its goal
| light and truth
Turning from the central audi
| torium again, we find in another
room an entirely new series of amaZ-
| ing exhibits. Over in one corner we
| find a case containing two small lead
| balls, which, when drawn toward
| la1ger balls by their mutual attrac-
ton, demonstrate the pow of gravi-
tation. On one side of this exhibit is
| a Nichols radiometer, one of the most
marvellous instruments in the world.
| which demonstrates the pressure ex-
erted by a tiny light beam.
Close Ivy Is a Nicholson inter-
| forometer, showing how length can
te measured in terms of light waves.
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