Evening star. [volume] (Washington, D.C.) 1854-1972, 1893-08-19
LOWER LM8.
Drawing of sun Spots.
UPPER Ln9

tObserved August Is. 1893 Astro Physical Observe
tory, Smithsonian 1ns;ifuuon.1
Is passed through prism reveal only a
part Of the story. how small part has not
yet been determined. For beyond the
field of colors there is an invisible spec
trum. and to make this become visible
and yield its secrets Is one of the objects
for which Mr.. Langley is working.
An Eye That Sees the Invisible.
When one thinks how vast the sun Is,
and that a body as large as the earth would
appear to observers here a mere speck on
its surface. there is something almost hu-
morous In the idea OF studying il with an
instrument 30 tiny that a hair would hide
on u stone foundation laid deep In the earth
In order that 1t may not be disturbed by
the footballs of passing people. But it
needs for his work is one ray OF light, and
to handle 1t and study 1t he must use the
most delicate apparatus. AIR. Langley
has perfected what he laughinsly spoke
of to a Star reporter as an eye which can
see the invisible spectrum. A prism male
OF salt as clear as the finest glass is used
to refract the light, and the refracted rays
fall upon an instrument called a bolometer.
This Is a minute and highly sensitive Their
mometer about the size of bristle. 1t has
an electrical connection with a gaiva-
nometer In an adjoining apartment, and the
wire through which the connection is made
Mr. Langley In explaining the apparatus
TO the Star reporter. spoke II as the
optic nerve. Outside the building is a
nat round reflector. more than a foot in
diameter, made of the most perfect glass.
ana ground to the most perfect fiatness.
Holding the SUN Fast.
The frame holding the reflector is in a
carriage connected with a very ingeniousy
constructed machine, SO adjusted that when
II Is In operation 1t keeps the reflector NOV
ing so as to exactly overcome the effect of
the earth's revolution. In other words, it
catches the sun and fastens it SO that it
can be studied at leisure. The reflected
rays pass through an aperture into the OBJ
seryatory, where they can be thrown at
VIII upon a screen forming an image of the
sun, an image which remains fixed and i'm
movable because of the nice adjustment of
Just now the image Of the sun is interest
ing because il shows the sun spots which
are attracting so much attention. A ray
of the sun caught on the reflector is pa ssed
through the prism and observations made
with the bolometer. When a dark line In
the spectrum is upon the tiny thermometer
lees II seeis .ne change In temperature or ex-
The observer. however probably could not
detect this If 1t were not for the Connection
with the galvonometer and It's delicate mag
netic needle. This needle is only one-siS
teenth OF an inch In length. L. is detected
IN response to the movements Of the bolom-
eter; It's variations. however could not
easily be observed directly, 80 attached 10 IL
Is device by means Of whicn the slight est
movement Is detected at once and makes a
permanent record. AS small as the needle
Is II has tiny mirror on tts end, a mirror
no larger than the point Of q pin A ray OF
neht Is trained by refectors SO as to fall
upon this mirror In turn the ray is reflect
80 SO 1t makes just little point or spot OF
light on screen few feet r.way IL the
needle merely trembles the angular move
ment Of the reflected ray is SO great as TO
make the spot Of light move perceptibly on
the screen. II the needle is detected to an
appreciable extent the spot Of light viii
make quite long journey horizontally
across the screen. and thus afford a means
OF observing and registering the readings of
the bolometer through the variations Of the
having the spot Of light thrown upon a son
siuve Photographic plate. The spot of light
moves horizontally: the plate is moved YER
ideally. The result obtained is curve
which shows the variations of the bolom-
eter; This In a general way gives an idea
Is exploring and mapping out the invisible
solar spectrum. The galvanomerer and its
little needle. 1t should Be stated, are secured
upon large stone slab. which has a deep
OF the building in which II stands This is
TO secure absolute freedom from disturbance
by any movement in the building or by the
Earring OF passing vehicles.
Recorded With a Pencil of LIGHT.
The galvanometer and it's tiny magnet is
the instrument through which news is be-
ing obtained of the present disturbances en-
the sun. The pencil Of light used to record
the oolometer observations Is now taking.
as telegraphers would say. a message direct
from the sun and writing 1t In Characters
tna5 scientists may some day be able to
READ plainly. Lines made by the moving
spot of light on a Photographic plate. rs TIE
magnet moved in response to an inpulss
9lrect from the sun. are reproduced In a
d draWrhs accompanying this article. The
Gays ago. 80 Affecting the magnet that tie
oolometer work had to be stopped Since
then n, the bolometer having been disconnect-
observing and recording the proRross of the