Evening star. [volume] (Washington, D.C.) 1854-1972, 1903-11-14
STUDYING SUN SPOTS
Important Work Being Done
at the Naval Observatory
WITH A BIG CAMERA
A PHOTOGRAPH OF OLD SOL IS
TAKEN EVERY DAY
How the Snapshots Are Made-Measur-
ing the Spots-Magnetic
Storms.
WITH A BIG CAMERA

Copyright, 1903 by John Elfreth Watkins, jr)
Written for The Evening Star.
Daily, for nigh on to six years. it has
been the wont Of Uncle Sam to steal a
portrait Of Old Sol, and. there being no
Joshua In these days to halt the chariot
of the god of day, these photographs of
his features have had to be taken by the
snapshot. process, in spite of the vast
chasm of 93,C00,000 miles which separates
him from us.
Receiving-by courtesy of Rear Admiral
c. M. Chester, superintendent of our naval
observatory-a permit to inspect this fas-
cinating work, l yesterday slung my cam
era across my shoulder and struck out
across the new Rock Creek culvert. 1t was
June morning in November, and Phoebus
at my back. burned with a fever which-fn
my imagina tion-bespoke some internal
seizure taking him out OF season. 1t was
cloudless day, only the blue, Indian sum-
mer haze resting on the hills; but alto
gether favorable above for the feat which
l anticipated. / climbed over the western
hill to the city of dazzling white mosque
like, round-domed buildings wherein our ma
tonal astronomers work. and followed the
path beyond where stands, in the Open the
colossal camera with which, under Ad-
miral Chesters direction, the daily sun por-
traits are Snatched from the heavens.
The Mammoth Camera.
This great camera is about fifty feet long
over all. Its lens stands isolated upon a
pier of masonry to the north. Its bellows
Is narrow, inverted trough-really a shed
with peaked, shingled roof-about thirty
eight feet long. It's box is a house wherein
men might live with comfort An unwieldy
snapshot apparatus for you or me to lift
md airf1a 1nft TO ho
airy, why is it directed toward the low.
northern sky whittier Old Sol has never
been known to stray?
l knocked at little white door and a
man stepped out of the big camera box. I
asked him this question, and many others.
as you shall directly see for he was the
man who for these six years back had
taken the daily portraits of the sun. had
been directed to Mr.. Geo. H Peters, one of
the naval observatorys scientific staff,
and this was he, most careful
methodical genius. as I discovered. A
a box which might have been mistaken
for a beehive by you or me-was lift
ed by Mr.. Peters from the pedestal of ma
sorry at the north end of the long appara-
tus. Thus was disclosed a metallic plate
on which rested two large disks of glass
That nearest the long shed leading into the
little house was mounted in vertical
shadows within the shed. This was the
lens of the big camera. 1t has a d:ameter
of five inches and will focus its image at a /
point thirty nine feet distant On the Same
metallic plate, but north of the lens and
mounted on slanting pivot, is a mirror
which gathers the suns image from tho
southern sky and projects :, back. south.
ward, through the lens. But to lool. at th;s
round piece of glass you would NOT s,,s
pect that it were reflector. Placing your
eye near to it you could see through If r.
is transparent and uns:lvered And inst &C
a piece of ordinary plate glass viii refiect
the suns rays. so will this unsiIyered ~
ror. But 1t casts a double refIection-nna
from the front and the other from the hsck
surface. If the two faces be paraiieI tha
reflections will overlap. But the s,rrf. ~ ~
of this carefully made mirror are sufIjciant
ly at an angle, one to the other tn throw,
one reflection of the sun eighteen inches
above the other. The lower and more ne,.
fect-that from the outer face of the pIacsI
is directed into the big lens, which Projects
it through the long shed or tube forming
the bellows, so to speak. of the apparatus
SUMS Candle Power.
But why is this mirror not siIyeredp To
understand this you must realize for a
moment the tremendous luminosity of the
SUM- To reproduce its light artificialIy Won
would have to travel $4,000, 600 miles AWAY
from earth and there arrange in the sky
cluster of one and one-half octiIIions (fif-
teen hundred and seventy-five billions of
billions) of sperm candles, weighing one
sixth of pound each, and burning 100
grains per hour. Such a tremendous light