The Milan exchange. (Milan, Gibson County, Tenn.) 1874-1978, 1880-10-07
Sun Signaling---WOrk Of the United
States GeOdetic Survey in Nevada.

States GeOdetic Survey in Nevada.
The Eureka New Leader gives some
interesting intelligence concerning the
work of party connected with the Unit
ed States Coast and Geodetic Survey,
now at work in that vicinity, under the
direction of Joseph Davis. The Leader
says: The present working headquarters
of the survey is at Arch Dome Peak,
near the head of Reese River, in Nye
County. From this point the entire adj
jacent country for radius of 200 miles
is being triangulated by means of hello
tropic signal lights placed on all prOmi-
nent peaks within range OF observation.
1t is for the purpose of establishing he
liotropic station on Diamond Peak that
Mr.. Davis visits Eureka and he will
leave tomorrow for that point, where
he will be stationed for five or six weeks
to come. The heliotrope is an instru-
ment used for signaling to an observer
at distance by means of the suns rays
reflected from a mirror. The instru-
ment in itself is quite simple. 1t con-
sists of telescope mounted the same
as an ordinary surveyors transit, adj
Unstable to any vertical or horizontal
angle, thus making it capable of being
accurately directed to any determined
point On the top of the telescope there
are two sights, much resembling a globe
sight on a ride, but considerably larger.
Back of these sights a small, adjustable
plate-glass mirror, three or four inches
in diameter, is placed, and the SUMS
rays, caught by this, are directed to-
ward an observer at a distance, the re-
Election Of the SUMS rays from the mir
rOr are seen by him, and it has been
demonstrated that this reflection can be
distinguished on a clear day for a dis
lance of two hundred miles. In the use of
the heliOtrOpe by the Coast Survey, an
exploring party is first sent ahead to de-
termine prominent peaks that may be
observed from a great distance from
the home station, and on these hello
troopers are stationed with their lights
until the locality, longitude, latitude,
and altitude of the peaks are definitely
determined by triangulation from the
home station. At present the Coast
Survey has one of these helitropers on
almost every prominent peak in this
section of the country, among which
are White Pine and Hot Greek Peaks,
Mount Jefferson, Diamond Peak and a
number of others that we do not recall.
They have also a monument on Pros
pect Mountain for the purpose of estab-
fishing the exact longitude for the Unit
ed States Geological Survey, whose
workings center at that point. Mr.. d.
Wis will have his station established on
n.,.I 81 IS =
when he will commence system of sig
mailing, with headquarters at Arcdome
Peak, distance of ninety-nine miles.
By means of a prsarranged system of
signals the heliotrope is used as a sort
of telegraphic communication, and Mr..
Davis movements and work will be en-
tirely directed by means of these sun
dispatches from headquarters. When
viewed from great distance these lights
are very beautiful sight, resembling
as they doan immense blazing star just
rising over the peaks on which they
are stationed. There is not a boy in
the country who has not, at some time
or other, exacted vast deal of amuse-
ment from dazzling the eyes of parties
at a distance with the SUMS rays reflect
ed from bit of broken looking-glass,
and upon the same principle the useful
instrument we have just described is
constructed. The heliotrOpe of the
lofty summit of a high mountain in the
same manner dazzles the eyes of the
far-distant observer with bit of look
ing-glass no larger than your hand. 1t
does not seem possible that so small a
rejecting surface could be seen at such
a great distance, but it is clearly dis
cernible, and at distance of forty or
fifty miles it is so dazzling as to hurt the
eyes The United States Geodetic Sur
vev is engaged in running on the thirty
ninth parallel, from San Francisco to
New York. Taking a strip of country
straight through, of an average width
of two or three hundred miles, the sur
vey is most thorough and complete
one and will establish the line of its
work with such precision as to make it
the authentic data for all subsequent
astronomical and geographical calcula-
tions in the United States. The survey
is moving eastward at very slow rate
and it will probably be several years be-
fore the Rocky Mountains are reached, a
point where the eastern division of the
survey will be met. Mr.. Davis informs
us that so far they have been engaged
nearly three years in the State of Ne
vada. This seems an unusual length
of time to accomplish the survey of SO
small section of country, but when the
extreme accuracy of the work is taken
into consideration it will be better I'M
derstood. The simple topography of
the country is not the only thing to be
determined by this enterprise, but the
longitude and latitude will be so pre-
cisely arrived at as not to vary even a
half an inch at any given point upon the
line,