The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1885-07-18
GEODETIC WORK IN INDIANA.

GE0DETIC WORK IN INDIANA.
The United States Coast Survey has long
been recognized, at home and abroad, as doing
the very finest kind of work. and its reports
have deservedly received the highest COM
mendation of scientific men. In compare
lively recent years it has extended the field Of
its operations inland, and has undertaken to
cover the whole of our domain with series
of accurately determined trianges, by which
multitude of exactly located points may be
obtained for present use and future reference.
One of the most important of these inland
series is the system which is to extend from
the gulf to the lakes, thus connecting at each
end with the orr ginal coast survey. These
inland extensions are covered by the term
''geodetic," and as the Omitted States Coast
and Ceodetic Surveys" this branch of the
Treasury Department is now known. 1t is
interesting to the citizens of Indiana to know
that the Indiana division of this Mississippi
valley line is in charge Of Prof. J. L. Camp
bell, Of Wabash College The Ken
lucky division is in other hands, but
both begin from a common base line
near Louisville, the Indiana survey working
northward and that of Kentucky southwark.
This common line extends from the Blind
Asylum, in Louisville, to a "knob" back of New
Albany known as Bangs" In 1873 Professor
through the State. selecting as nearly as pos
sible the practicable route for such survey.
This was completed in 1881 and the stations
reported extend north ward from Louisville
through Seymour, Columbus, indianapolis (the
court ouse being used as one station), Roches-
ter, and so on to South Bend, where connection
is made With the original lake survey. In
1882 the work was interrupted by the Kanka-
kee survey, of which Professor Campbell had
charge. In the following year, however, it
was resumed, and ever since it has been
pushed forward as rapidly as summer vacations
would permit. Thepreliminary reconnaissance
over, it remained to begin the detailed work
of the survey, which is follows: Four
points are selected, which must be as
far apart as possible. must form reason
ably good quadrilateral and necessarily inter
visible. Two stations Of the first quadrilat
eral had already been selected, in com
mon With the Kentucky survey, viz, the
Blind Asylum at Louisville, and "Bangs"
Knob, back of New Albany This quadrilat
eral was completed by the selection of station
Sims, at Utica, and station Six-mile, on
knob overlooking the Louisville, New Albany
& Chicago railroad, at Six-mile switch. The
measurement of angles must be conducted
with the very highest degree of accuracy, or
the work will not be accepted At each station
in each quadrilateral three angles are meas
ured, and the repetitons required cause each
angle to be measured at least seventy two
times, so that at least 216 measurements are
made at each station. The averages are then
TAKEN and the results show measurements to
the thousandth part of second. No such
fine mathematical work is being done anywhere
else in the State and the consequence Of such
extreme accuracy will be that the position of
the station selected will be exactly determin-
ed, and all local surveys and map
ping can be referred to them
as reference points. For instance,
when the indianapolis court house is occu-
pied, its exact position upon the face of the
earth will thus be determined, and it will
become center of geographical reference for
all future time. The first quadrilateral has
been completed and the second partly so,
while the third is outlined, its stations es-
tablished, and it only remains to measure its
angles. These stations are rendered perma-
nent by a very elaborate system of surface
and underground marks, the centering being
so exact that the central mark is the tip of a
copper wire. AT some stations temporary
towers are constructed, sometimes fifty and
sixty feet high, to enable the observers to
overlook obstructing timber. -Four such
towers have already been built, one on
Bangs Knob, another at Utica, third near
the Clark county poor-farm, three miles south
| of Charlestown, and the last about three miles
north of Charlestown. Upon the KNOBS
towers are not necessary, simply tripods being
erected for carrying the centering poles and
signals. The lines thus far have varied from
five to twelve miles. The northernlne of the
third quadrilateral is nearly upon the northern
confines of Clark county, which to an out
slider might seem to be slow work; but when