The morning news. [volume] (Savannah, Ga.) 1887-1900, 1896-04-12
A SECRET OF THE SEA
THE UNRRRING WAYMARKs OF
THE TRACkLESs WASTES.
How the ."LOneIy Mariner" Deter.
mines the Position of His ship il
the Wilderness of Waters.
From the Philadelphia Ledger.

the Wilderness of Waters.
From the Philadelphia Ledger.
In that beautiful resting place of Il
dead, Laurel Hill, repose the remains
Thomas Godfrey, Philadelphia, and OF
Of the inventors of that instrument so il
valuable to mariners-the quadrant of r
lection" By trade a glazier, his absorl
ing interest in mathematics caused him
study Latin, in order to read importal
treatises. His experiments were mao
with two pieces Of looking glass. and !
apprised Hadley of London of his instr
mental discovery, but Hadley claimed
similar improvement as his own. tt
Royal Society, however, awarded a join
honor, and Godfrey received prize of 20
As Newton had previously suggested tn
use of the rejecting principle we may son
slider it as having three independent lis
coveries. The quadrant has given pac
to the sextant. but its principles are m
bodied in the latter, and we shall sc ID
this paper what an important relationlaej
bear to the vast commercial interes Of
the w9Tld. IN H9tl
Let us abduct from his quiet observiory
the astronomer who spends his nigh in
industriously scanning the heavens and
surreptitiously introduce him to the bin
of vessel taking care 10 keep hisyes
perpetually bandaged We will keephim
literally in the dark concerning our pve-
ments for a whole month; and on pine
bright morning we will remove the zap
pings from his eyes, and, merely Ting
him the day of the month require hi to
inform us of the position of the ship.
Our astronomer will smile at theim-
plicity of the riddle, and ask foithe
ships sextant' and chronometer whit lis
set at exact Greenwich time upon 'av-
ing port, and a copy of the nautici al
manac of the current year. The latteIub-
hcatlon by the government is preired
with great care and may always bhad
three years in advance, for the befit
of vessels on dong voyages. 1t is atOst
substantial and clearly printed volui of
800 pages, containing tables of the ms
right ascension and declination the non's
movement among the stars, the epine-
rides OF the planets and various phOm-
ena of the highest value to the Wcing
astronomer. The predictions of solaand
lunar eclipses which are found in theop-
ular almanacs of the day are borsVed
from the toilsome computations conned
in this famous blue volume and THAR
liner looks upon it-in connection wi his
'Epitome," Bowditchs Practical avi-
gator'-as his oracle. And yet theihas
probably been no annual edition intolich
some slight inaccuracies have not slieed-
ed in creeping.
The Instruments Of the observory.
which rest upon a stone pier discounted
with the framework of the floor the
building, in order to prevent the sltest
vibration are utterly useless at 81 be-
cause of the mobility of the vesse and
the great value of the Sextant lies the
precision with which it measures aular
| distances while held in the hand the
| observer. "A
1t is a brass sector of a circle; ithape
to coin homely, illustration-thtof a
sixth part of pie. An alidade, orova-
| BILE arm, to which is attached lie in
deX mirror" turns upon a pivotI the
radical point of the sector thus limit
| ting one end to move freely aid the
half degrees numbered as whole Oh, be-
cause of the angular effect of 4 dole re-
enables the observer to obtah aane
| graduation as ten seconds.
| A second glass, called tie brizon
| glass" half of which is silvfed ia the
other half transparent, is ked } the
frame of the instrument, andwher1e OBJ
| server moves the alidade 81 thatne re-
| tected image of the sun is TOUCHDOWN
| to coincide with the watt linen the
horizon glass; the readinPf themb of
the seXtant will at once shy thehgular
| altitude of the sun at thehomenof OBJ
| servation. The image is fewedvith a
tiny telescope; and a shf glasds en-
ployed to shield the eye. Ehe exIriment |
/ may be made on shore WI an 'Ttificial |
horizon which may bel basinlf mer- |
| curry, water, tar or mol3es.
If our astronomer pubses. talng the
4 mence to observe that OF about Quarter |
| of an hour before noonH oldinglhe sex |
| tant perpendicul2rly, will bng the |
suns limb to the horif. and, b means |
/ of a screw, gently inASe the lngle as |
| the sun ascends, unthe MAXIMUM is
| reached, and the suneS1nS to din -
The latitude of anyace Qts distance
/ from the equator) is insured by m arc of |
/ the meridian containLoetWe tie eoua-
/ tor and the zenith; sotlt II the zelith dis
/ lance of any heavenDody, whei on the
/ meridian, and also L decllnat TIM are |
known, its latitude De lmmeditely an
Assuming that ODE day in question
about the summer fl.e;e, the sur bearing
/ south, the meridif litude, AS read on |
| the limb of the Sept, We're 40 kegrees 6
minutes there WI need to BIT applied
several CORRECTED of "para1ItsT%i
or the difference POSITION of the sun as
viewed from thebter of the earth and
from point on surface; of "oip of fhe
horizon due toe elevation OF the oh
/ server: of s'serniEneter of the sim > be
| cause the transE ats center is the truo
| factor and of fraction" an atrnos
pheric' ph i The three former former
/ would add perf Il minutes to the aIfi-
| tude while thtter might subtract one
minute The It-4O degrees Il minutes
the true altf would then be snh-
tracted from Iegrees (the ansuar ais
lance of the n from the horizon). Civ
| ing as the sufue zenith dist ance 40 de-
grees 43 MINI north; The suns "decli- |
nationi a. thne OF observation as fonnd |
in the almaI 20 degrees "a Minutes |
north. mustf be added, which gives ne
the latituddne Nessei position as 70 |
degrees 10 II es norm.
If howell were the time of the win
ter solsficI same reading of the sew
tam wonid fcate the latitude to he onIv
26 degrees linutes north. for the SUMS
declinaffobw, 3 degrees q minufes
south. wa have to be subtracted from
me 1sni, ance.
AS Vet 1lave only learned how far
norm or I we are. and as the parallel
of latituI many thousands of miles
in exfenI must discover our east and
west nol. But this is very easv. for' ,
a. mo ~ the obervation is s'apparenf
noon" 4 vessel. Il Is only necessarv /
10 dnd INFERENCE between II ana The
Greend Inc indicated by the chrono- :
meter I, too. stands al noon. the 49, !
sci b longitude OF Greenwich: IL n :
reajr flock. the vessel Is two holIrs 4