The Hawaiian gazette., 1875-05-05
Progress ofthe Government Survey.

Those who are interested in the progress of
this enterprise will be glad to know that Sc
ries of triangles forming the frame work of the
survey of Oahu has been completed by Pro-
fessor Alexander, the final junction having
been made last week by a line nearly Is miles
in length, joining the station on the promOn-
tory of Mokapu, in Kaneohe, with that on the
tongue of land at Laie, few miles from the
extreme north point of the island. The third
point in this final triangle is on the summit of
the sharp peak at the common head of the Wal
kane, Hakipuu and Kaaawa valleys. The
whole series of triangles numbers about thirty,
with sides varying from three to eighteen miles
in length, the whole circuit being over one hun
dred miles. In determining the position of the
Laie station by progressing from the original
Waikiki base around by Makapuu, or east point
of the island, and also by progressing around
through Eva and Waialua (by the west), the
difference in the two results is found to be not
over tDOt feet; certainly not dangerous error
for hundred mile stretch of survey while the
direction, or azimuth of the joining line as
likewise determined from both ends of the sys-
TEN, was found consistent with itself down to
a single second of arc. This speaks well both
for the l2-inch theodolite, and the manner in
which it has been used
Hundreds of secondary triangles for district
work have been or will be measured from the
primary series across the channel to the ISL
ands of Molokai and Lanai, where the connec
ton and verifcation can be made with the
Maui system. For signals to be observed at
such distances an ingenious little instrument is
used, long known in extensive trigonometrical
work 1t is called the heliohope; by the Brit
ish observers heliostat; and consists simply of
very perfect little plane mirror mounted on
a tripod, with sights and apertures so arranged
that the rays of the sun can be thrown in any
desired direction without materially losing
their power by divergence. This diminutive
arrangement stationed on Molokai, was actually
distinguished with the naked eye on Monday
before last from Mokapu, a distance of about |
forty miles. There is hardly any doubt but
that with a clear atmosphere and good tele-
scopes, it can be seen as far as the curvature
of the earth will permit Added to this, it can
be readily used with little practice as a
means of telegraphing any little bits of infor-
nation required by the operators.
1t should not be imagined that because the
is completed, Oahu is surveyed.
A great deal of strictly Gland Office Work :"
devolves upon the department, and only those
with the land system of these ISL
ands can have an idea of its intricacy, and the
labor attendant upon the faithful survey of any
district or portion thereof, so soon as bounda-
ries are to be mapped out. A thorough chart
Of the coast, with soundings from Dimond
Head to Barber's Point, IS in course of prepar-
alton conformity by the Government Survey and
he officers of the o. S. s. Pensacola, under the
direction of Admiral Almy. The coast-line of
he whole island will soon be delineated with
accuracy, the accomplishment of which nation
II duty will form really an era in Hawaiian
civilization. As the public are welcome to
whatever information can be given at the office
If the survey, and as the work is for general
benefit, it is hoped that all who have Informal
ion to furnish in the way of maps, any ways
elisble, or in other methods, will not adopt
he too common idea that the Government is,
ike haoles, to be made to pay double price for
required. :