The Scranton tribune. [volume] (Scranton, Pa.) 1891-1910, 1901-03-08
SPEAKING BY SUNLIGHT.
How the Heliograph Was Used in
Many Wars.

From the London Daily Mail.
Most of the news which came from
Ladysmith during the siege was trans
mitted from the beleaHuered town To
General Butler by mesns OF either the
heliograph or fiashlight
Eight hundred years ago North AZ
frica had system OF wireless teleg-
raphy by which places a hundred miles
apart could exchange messages In a
few seconds. In Algiers buildings were
erected on prominent sites over the
land. with adjustable mirrors on the
roofs. The suns rays falling on these
mirrors were flashed in the sky, aud
were visible at great distances. II
was easy toarran &c a plan by which
the flashes of different length should
mean various letters and so make it
possible TO exchange conversation.
Then the world went to sleep. and 1t
was not till the time of the Crimean
war that the possibility of talking
by sunilash began to arouse attention
The Russians used mirrors for this
purpose largely when they were he
siegcd at Sebastapol and this led the
English army to examine the matter
but 1t was not until thirty years later
that the mirror telegraph" as some
called 1t, was adopted by the Indian
army.
In 1885 experiments were begun by
the English army with the heliograph.
and they We're so satisfactory that
four years later every regiment and
battalion in the service was supplied
with two.
Since then there has not been a mill
tary campaign without abundant de-
monstrations of its usefulness.
In the recent campaigns against ma
tive tribes in Northern India the hello
graph was invaluable. and by 1t the
most outlying posts were kept in con-
stant touch with headquarters. Your
| enemy can cut the wire of your field
telegraph line; he cannot intercept the
flashes of your mirrors.
Many years before this. in the
Transvaal war of 1880. one of the be-
sieged British garrisons tried by every
possible means to open up communi-
| cation with other British forces many
miles or. Runners were Intercepted,
messages never got through. At last q
| bright idea struck one Of our officers.
| There was no helioGraph with our
| troops, but the officer got q shaving
| mirror and used an ordinary cloth
! cap as a shade. lie put the mirror at
an angle to reach where he thought the
| British relief column might be, and
| started flashing In the sky by quickly
covering and exposing the mirror with
| his cloth cap. At first came no re-
| sponse.
The work was continued. the signal
| work being flashed around all likely
| places. Then there came ID flash back
| from the distance. With straining eyes
| and beating hearts the beseged mon
| read out the signals sent from scores
| of miles away: "All well. Relief
| quickly coming"
| What Is the heliograph? Briefly, it.
is "a circular adjustable mirror or mir
rors, usually mounted on tripod stand
| and with a sighting arrangement at
| tached. The mirror is adjusted until
the shadow from the sighting rod Che
| rod which stands out in front of the
| glass; falls exactly on an unslvered
| spot in the center of the glass The
| unsilvered spot. the point of the sight
rod, and the distant object which 1t Is
wanted to reach have to brought in
the same line of sight.
There is also a rear screw arrange
| ment by which the mirror can be
moved to the right or left without
disturbing the sighting. so as to fol,
low the apparent motion of the sun
A shutter is so placed that it inter.
cepts the DETECTION from the mirror
which is operated by a key at th-
bottom of the mirror.
The operator. by depressing the key
| tla.a tV.,., a.
flash of the light to be reflected. A
short depression reflects short flash
and 4 long depression a longer fash
This enables the Morse alphabet TO be
used-the ordinary dot and dash sys.
tenn of the telegraphic instrument.
The distance which these sun flashes
will travel Is hardly credible. The rec.
ord was made by Captain W. A. Glass.
ford, of the United States Army Sig,
mailing corps, who, in some experiments
in Western America succeeded IL
opening up and maintaining communi,
cation between Mount Ellen. Ctah
and Mount Uucompahgre. Colorado
hundred and eishty-threc milei
apart. He used an eight inch mirror.
The larger the mirror the farther /
is possible to fash. The ordinary Eng
llsh service pattern is five inches il
diameter.
IT is only in very clear sunshiny
country that long distances can b
covered. In England it would prob
ably be impossible to send a MESA e
more than twenty miles, save unde
uHusual conditions. our climate make
the heliograph comparatively usoles,
here.
When it is required to send u mes
sage 10 place in such direction
that the operator stands with the sun
behind him, "A duplex mirror has to b,
used. so that tha suns rays are caugh
on one glass and sent back to tn
other. This involves careful adjust
ment, and is sOre complicated THAI
when the sun is in front.