, 1885-05-22
- - q AELIoaaApAY
Description Of the HeliostAt-How It Il
workad-Limited Usefulness.

Ooa'riptioh OF the nonoathh-AoN
w-orkad-Limlted Usefulness.
fFr,dA 4. Hunt in Chicago Neusl
The heliostat-the proper name-is
used with success in the Soudan, and
has been used with much success in
America, as in Montana, before the in
PRODUCTION OF the telegraph along the
Yellowstone valley, there were a series
o. heliostat stations between Forts
heogh and Custer But the heliostat is
a troublesome instrument at the best
for the sun is not at all times available.
In the Soudan, where the country has a
vast extent of plane s~urfnee, heliostat
stations can easily be erected, and, the
SIN being n pretty constant factor, mes
sagos are easily transmitted, but in o
broken or f.mbered country, where the
sun becomes clouded, the heliostat is
no so reliable or useful, and one tele-
graph is oorth a dozen heliostats, i
The heliostat consist of a circular
mirror four inches in diameter, mounted
on a tripod, provided with suitable ad-
justments, 10 that the suns light van
be rece we'd upon it and reflected at a
distant station. So far, correct; but
it additionally has a small rod attached
to the top of the mirror rests, which
has a small amount of perpendicular
play the vertical oscillation deter
minatie by set-screws. To operate 1t
the telegrapher seizes a little button on
this rod and ~''jiggles" the mirror up
and down; a long Jiggle makes the tele-
graphic long dash, a medium jiggle
the telegraphic dash, and a short jiggle
the telegraphic dot, and combinations of
those three signs, according to the
Morse code. form the mean of sending
messages. The receiver simply watches
the flashes of sunlight, and the duration
and the intervals between the flash are
read by him as readily as though he
We're receiving from a telegraphic
'sounder. One is optical telegraphy
and the other aural, that is all the
difference. at
10 learn the art of photography the
sender takes the button, just as a tele-
graph operator does his key. and APP
plies his eye TO the center Of his little
mirror. In the center is a spot without
any mercury, and through which the
operator can see. In front of the hello
stat, and distant about two yards, is
placed an upright wand with four dis
tinct marks on it, making divisions on
its verticality, the lower n being half
the length OF height of the next, and
llt lASl ulNlolOu Dbluk lMlCt luC AthbAl
of the first; something like a yard-stlck
with one-quarter, one'half, and a yard
notches on it. The operator defects
the mirror, and a sunbeam glances up
| the stick; according to the depth of the
'jiggle'i or detection the sunbeam
dances higher or less high, and then the
operator understands that the sun
beams Jump from the first notch up
ward to the second is a telegraph dot,
from the lowest notch to the third notch
is a dash, and from the lowest notch to
the upper is a long dash; the vertical
length of the depression of the button
answering to the period that a tele-
graphic key is kept down and the cir
cult is left open. .I aa'r
/ have seen messages read Just as
readily that were sent from q station
thirty miles away, as though received
from a sounder at ones car, but tho
proclivity of the sun to get behind a
cloud or retire from heliostatic service
at importune moments seriously mars
the efficacy of this beautiful and scien-
tiic little instrument. They are readily
transported and easily adj listed. But
for field service in any country or in
any condition Of atmospheric change,
the torch signals by night, and tho flag
signals by day, Of the United States
signal service, are certainly the most
efficient and reliable, while for long dis
tances between stations, FIRE flashes at
night and smoke-with interrupted
smokiness-for day are the best In
dams have longed used mirrors as the
means of conveying intelligence, and
the idea is utilized in cable messages
in precisely the same form as in the
heliostat. Indians also use smoke for
signals, making flashes by covering
the smudge with a wet blanket and then,
by removing it, allow another gust OF
smoke to arise in the air. Possibly this
may 10 the origin of the proverb about
throwing a wet blanket on the mat
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