The New York herald. [volume] (New York [N.Y.]) 1840-1920, 1878-06-06
How Sandy Hook Lightship May Be
Made in Thick Weather.
A DANGEROUS SOJ7HWESTERLT CURRENT.
Captain Trudelle's System Of Indirect
Approach by Soundngs.
UNRELIABILITY OF "DEAD RECKONING"

alence OF logs on the New Jersey and Long
Island coasts. These fogs attributed TO meeting
Of the cold OF tho Arctic ocean and the
Euf Stream and certain seasons OF tns year tbs
melting OF ice foes carried down 10 the sea by tho
rivers. These logs come up very suddenly and some
lines continue days. so that navigalors CON-
PEELED to depend wholly upon tho correctness or
their 'sdead reckoning" 10 calculating their To-
cation. The unreliabi!ity OF this method Is
further increased by The existence OF strong cur
rent which and about the rate OF
miles per Thi, current is. however intermittent
sometimes either II does exist At all or IL ia
scarcely percepiole. For this reason, perhaps has
received from navigators the attention IL merits.
The credit OF having carefully investigated the COM
biued inf uence OF these logs AMI the southwestery
current in aking the approach TO danger
during oggy weather belongs to Captain l. Tru-
dele, OF the French Transatlanque limo Of steamers
This gentleman's attention was called 10 the number
ships lost by navigators trusting 10 "dead reckon
ing ana in many cases where the officers in charge
apparently acted with prudence and judgment
CAUSE DISASTERS
Captain Trudee alter carefully stud ling The subject
to The conclusion that the system approach
,Dg the New Jersey coast straight course during
oggy weather has been the of numerous marine
disasters, which the adoption Of moro scientific
lystem of navigation would have prevented In tho
Eel-known cases OF the Amerlque the Vcks burg and
The Queen, the disasters 10 these vessels clearly
sraceable 10 the same cause.-the imposslbihty OF
making out the exact position OF shin during
foggy weather by the old method A close study OF
this subject showed the Captain that the sound
along the usual direct course could not be re-
lied on to decide the exact position OF ship
approaching the coast. because The depths OF
water are found under very similar conditions at
varying distances. In some cases a navigator might
ug gecm 10 nuic Ia thnth a
twenty thirty miles of shore when IN reality
he might be not more Than two or three miles distant
from The coast yet his soundings would agree with his
supposed position the chart. IL viii! be
That the terrible disaster which beisi the Atlantic,
oil tho White star line, due this trusting 10
dead reckoning" and sounding. without giving que
importance 10 the influence OF surface currents,
which may Cause a serious deviation from The
which the navigator imagines he Is following.
Convinced great danger arising from the unsal
isfactory conditions under whch ship approach
New York duriug the prevalence OF ioggy weather
Captain frudelle himself study
and scientific way which would eliminate the
element Of chance and restore navigation to the
sound basis OF precise science As result OF these
stuaes a system has been formulated and reduced 20
practice which promises to remove ali danger 10 safe
navigation from the causes which led 10 Inc loss Of
the Atlantlc ana Inc wreck oil many
ships on tho New Jersey coist Tho sys-
tenn is simple II promises to be
effective 1t is based the well known existence Of
two curved lodges running parallel to the nue.
The irsl OF these is encountered by snip approach
ing the coast NJ distances varying from 80 10
" nautical miles between latitude 40 DEG. 10 min.
aud 40 des. 40 min y. This ledge is known TO
navigators as the thirty fatpom line, and clearly
tered between latitude SO deg. 81 min. and ~ deg.
NJ, anu is SHOWN as The twenty iatnom line. No
matter now ioggy the weather MAY be u Is claimed
that u snip advancing iron the thirty atnom me
a course : 65 deg. W. can always Dnu this twenty
fathom lDe II only due attentonis PAD TO tho sound
ings. Once this line has been reached a vessel
changes her course due north, ana can reach the
Sandy Hook iiahtship without danger Of getting
stranded. as her course lies parallel 10 the coast line
and offers I'll Guilty navigation, because The
position Of The sup be Determined by sound
ngs-
Captsin Trudciie put us theory into practice
with tho sth OF May 1871 Amer making
the twenty IaLhom line he changed ms course
que north Tor distance Of III nautical miles.
taxing, in tnat distance, three soundings-tno
oms, with mud bottom. Three miles further
the lead showed a sand bottom and - Il iathoms OF
waer. The next casting OF mo lead gave IL lahoms
OF water, wtn a sandy bottom. The SHIPS
laid due west for
teal miles, when IL VAS again laid north. The hrst
cast Of the lead on the westerly course was taken
when the snll had made Jour aud hall miles, and
turner gave is fathons, winch. al nine miles,
dminishca 70 lSlz iathoms. run north OF three
mites brought Tue snip within ave miles o. the
Sandy HOoK ighlshp, ~ l9s tathums OF water. Good
observations allcrward Obtained showed thai tho
tuai position OF the snip was only Two miles oil IRON
4 SECOND EXPERIMENT.
On tho l4h OF March. 1875, captain Trudellc, nav
Ing experienced Two ioggy days which prevented
him taking observations when ABOUT aiy mi cs from
the coast laid his course south, 90 deg W, aud
after n run Of about thirty M les "a sounding was
made wnicn showed 23la lainoms, with a sandy bot
tom. second sounding, TOUR mlIes TO westward, gaze
tho same dcpth III water and a IN ra gave "a from
ma IN r. al a md half IN las Wert.
ing brought the snip 10 the 20 lathom inc the sound
Ing giving 1875 iaihoms. Tue snp's course VAS
two soundings takon--iho nrst when the ship
baa proceeded Ave miles on the noriherly course
showed - iathoms OF water and mud bottom, mo
second taken iour miles further north gave 1914
iathoms Inc course was now lad west by north Tor
nine miles and three souGungs taken at tnrcc anu
hail, seven hal and mites, giving respect
lively IL li anu 10 iathoms. Tue course was now
laid due west or two ana seventeenth nautical mites,
two soundlngs giving II and 10 fathoms water. tho
course was now laid North 10y vest tor about three
miles and bali IN this run eight sounaings were
taken They showed the depth Of water 10 BE- Is "a,
H. TO- l7t, II, l6, 10 and 10 lalnoms wDen the sup
came 70 anchor. On the log hitting q was discovered
that The ships true position was throequariars oil
milo N. N. h. VI sandy Hook lishtsnp
SCIENTIFIC PRECISION
The great protection offered by TINS system Is due
10 the Darrowing down OF the extensive locus, or
mathematical limit B, A. b. TO the snort line O.,
aud the conseque nj lessenng OF the dangers arising
iron characterization. whie ships advancing west
along the direct track now generally uso1, between
40 deg 10 min ana 40 deg az min n LATITUDE are
unaoie when caught IN log, to ascovcr their exact
position within the mathematical nmits b. A. -,
ships adopting Captain Trudee's broken track can
advance securely westward I'll they strike the so
falhom curved line and tbcn, steering s. o. deg. W.,
iii they come TO the second curved Line. marked
q tho map, thereby reducing their
mathematical limits within very small area.
Their latitude shall then DO included within
80 deg. 81 min. and 40 deg. y. latitude and their
longitude between 10 aeg ~ min. 70 deg 90 mu.
Greenwich. The navigator at once gets rid OF all
orialnaI errors upon tnose two elements, aud by
changing has at once or NJ the hrst sounding
marking IL or 20 athoms ne changes the wide aud IN
definite Iocus Is, A. b. Tor ane, with tho certainty
that any error longitude does not exceed or
minutes.
ONLY gEEps CARE
The north course IRON this line TO the sandy
Hook lightsnip can be safely followed by careful
soundtnEs, no matter how loggy the weather may
be, the loci or mathematical limits ID u DID
~. afford the means OF accurately determining tDo
snp's position. The latituae OF tue last must be 10
aeg. Ii 10 40 deg. IL min aud the ongtu will
be nxed witniD 2or minutes The stric Application
Of this system does away with the rule oi thumb