The Hawaiian gazette. [volume] (Honolulu [Oahu, Hawaii]) 1865-1918, 1874-06-10
National surveys.
eating spirl

National surveys
These are empbatiealy days Of science and
utility. The theoretic and the ideal, science and
art. are becoming more and more tributary TO Ia
Dor. and the common necessity Of use.
Among the adaptations or combinations. Of
science and utility. there is perhaps none more
important than that Of astronomy TO the surveys
\ Of extended surfaces Of either land or water.
Astronomy is pre-emineu,ly science Of &C
eA,acy, as much so. indeed, as Il is science OF
exiASme grandeur aud unlimited scope; dealing
as ID aoeS almost with the very space in which
creation lies. This, then, is the science to de-
Iineate line Of dangerous coast. detail the posi-
ton Of hidden rocks, or if necessary, map whole
continent This system Of higher surveying has
been brought to its greatest perfection IN the
Ordinance Survey Of Englard and the Coast Sur
vey oE>ehe United States. This latter especially
JSS marvel Of accuracy, inexPensiveness. and
rapiiity. Though requiring great nicely OF de-
tail and consequently much scientific skill and ex-
psrience in its working out, the plan is quite sim
pie. and may be very easily understood,
The first. and BY far the most important and
difficult step, is the trangulation. Imagine your
self on a plain, surrounded in the distance by
PERCEPTIONS mountains, the exact relative posi-
tious and elevations Of which are required. ow-
ing to intervening difficulties their SUBMITS can
not be measured TO directly, so il must be done
indirectly, or by triangulaiion. A base Of con-
yeuieut length may be measured anywhere, as
accurately as possible and the angles with it and
the desired peaks also measured. and from these
data by simple theorem Of trigOnomelry the
distances and elevations may De easily ascertained
Take another instance Suppose the distance
from Haleakaa 70 Mama Kea be required Any
direct measurement is simply impossible. TRAN
guIati0u is therefore rssorted to; base is mea-
sured on the level is,hmus Of Maui, from which
the distance from Haleakala TO Hahoolave is OBJ
taiued which forms an excellent base for the dis
lance from HAleakala to Mauna Hea. Nor are
these extreme cases. bat such rs must occur con
tinually 10 mountainous country.
Even in case the nature OF the country is such
as to admit Of direct measurement, trianguiation
is by far the least expensive and most accurate
method. as 1t requires the measurement Of only
one line, instead Of hundreds over even ground
Instead Of broken; and with greater accuracy
than could be maintained through q number Of
lines. Hence scientific and practical men have
loug since come to the conclusion that triangula
ton is not Only the least expensive but also the
only accurate available method Of surveying large
regions A network Of trianguatiOn is thrown
over the whole country. winch forms the frame
work for the miu1tiS and Is as absolutely ueces-
sary TO large survey as the frame is to large |
house.
The accurate measurement Of base Is not the /
easy undertaking that it may seem. Ia the first .
pIsee it is not every day that good, level unbrok
en- stretch OF country, 5 or miles long, and con
venieutly placed for trangaatiou can be found, aud
very frequently expensive and protracted grading .
hss TO Be rezcrtsd to- For ths actual measurement,
metal bars are generally used, Composed Of brass .
aud iron, arranged that the difference Of exPdu.
sion viii exactly balance the total error due 10 this
cause thus uaiutaiuiug the same length at all TEN
7eratures The inclination Of the bars also has to
be overcome or accounted tor. Nor is it an easy
matter, always TO bring two metal bars in contact
iouary one and thus bsving to 20 back TO the start
nE point. Tbfs difficulty is overcome in several
ways, the most satisfactory perhaps is an arrange
nsut Of 6ue hair spring.
By means Of these most improved instruments,
md great care, base Of or miles in length may
be measured, with probable error Of only small
actiou Of an inch To maiatsin this degree Of &C
,uracy requires that the angles be taken with the
finest Instruments, and under the most favorable
circumstances Of atmosphere aud weather.
Tie Coast Survey use a so inch theodolite, with
which the angles are measured TO fraction Of sec
,ud. and second is an exceedingly small quantity,
az an inch in ten miles This instrument can be
,ssd TO advantage but or hours out Of the most
avorable day For smaller triaugIes, and filing in
De Details much smaller and mors portable iustru-
neBts are used TIE zoaudiHEs, &c, are also at
achsd 70 the shore stations BY system Of triaugu-
alton.
Tae benefit Of accurate surveys ziil probably be
appreciated BY all On the correct mapping Of
COST, depends the lives aud commerce
4 hundreds ofvssssIs= and whatever Affects the com
neres Of nation viii rot be Ions in affecting its
-tal welfare.
A. landed property Is at the bottom Of all wealth
u Intimately connected With it, it Is very desirable
hat t should be 50 Accurately aud correctly defined,
as to iisperse all doubts and in any country the
educiiou OF the surveys TO one system and stand
I'd Eith an underlying triaugulatiou would be the
aviug Of az immense amount Of unnecessary Iiti-
.atiou.
such surveys are Of great value to science in many
gays. When extensive enough, an arc OF the meri-
ian nav Dc measured from which the size and
zure Of the earth nag be computed Many geoIo-
DC and geographical facts are continually being dis
overed the existence, rate and direction Of ocsan
urrents settled; the rate Of growth Of corals and
and banks ascsrtaiued; and a hundred other
hiugs; besides the splendid scientific collections
bat nay be made in connection with them.
a Poor Excuse.
70 he Editor a he G1-stts
The fOIIoEiuE extract from the last Afrs7fiss7-,