New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1892-12-25
A KNOT AND 4 MILE,
now NAv1GAToRs COMPUTE DISTANCE" DEAN
RECKONING"

HOW NAVIGATORS COMPUTE DISTANCE" DEAN
RECKONING"
"VIn you please explain the difference between d
knot and mlle?n "WlIat Is the meaning Of the term
knot as applied to the great speed made by the City
OF Parsln :" Is not the term knot simply a unit for
measuring the speed Of vessel at sea- and has any.
thing TO do with The actual distance that the vessel
makes In Il specific timer These only some Of
the questions asked by a subscribers constant
Readers and scores OF others whose letters arrive by
each mall and each requesting repy, some inclosns
slip Of paper and addressed STAMPED envelope some
with stamps only and many with neither stamps nor
money the writers having thought that the answers
to such correspondents involve not only expense TO the
newspaper Of employing persons to answer these let
ters, but there must also be added the cost Of station
airy, postage. etc. Some writer's also neglect to give
their full Names others fail to give their address
that many letters cannot be answered. This latter
class no doubt CHARGES the editor with indifference,
while the fault IS entirely with the writer who neecti
to say TO whom ard where the reply IS to be sent.
But what +, tie meaning Of the word knot" It's
purey ana wholly nautical term. having specific and
direct application TO the speed and distance made oy
a vessel moving in water. The word knots is the
mariners nautical mile, and its use Is really
derived from the log line used By navigator; OF the
ocean when they Wish to determine the speed and the
distance that the ship has probably sailed IN gwen
tine The log Zinc is an important and very neces.
sary part OF ship, fittings, especially is this the case
whom for several days at sea the NAVIGATOR unaDe
because Of tie sun being hidden by CLOUDS or InCS
weather TO cct peep nj 1t with his seXtant from wnlcn
the ac1ial position Of tho snip j. worked our. WIZ
the data taacn ly Il frequent heavng q the log "a
snal block or section Of wood with long line attached
and run out from tie stern oil the vessel for speclic
ruaier Of seconds noting the force and erection OK
the wind the possible MIS- or other Influences acus
favoraby against the progress Of the ship the nael
gator Is enabled to calculate very nearly IN overcast
o. III, day Thi, is called working out the position "
The slip bY dead reckoning - ST..
early school days will recaE that part Of The sing,
son. recitation running like ths 80 10 statute miles
nj tie equator Now the difference between statute
mile and nautical or geographical mile IS that N?
later about SOS feet greater Iaa Inc or Of aners
80 Geographical miles to each degree OF !ltude or
10 90 degree OF longitude at the equator. WHICH
divisions Of mics ar" called minutes n the nauuca3
vo ahulary. hence the old saying "a mile minute
4. there are 800 degrees m"idians Of longitude
there 2l.GO0 minutes or miles In the entire err
cumfercnce OF the world, az the equator ana II mas
been ma Dramatically determined that one ninute-0na
geographical me-at the equatorial circle + equT 10
o-G7 feet But IL has been the practice OF mariners
not 20 be too exact on small fractions when measuring
distance as great as a mile. consequently the Pacucs
Inln, hnot or nautical mile as equal TO $3.50 teee
instead Of $685. feet. has been generally adopted
when the navigator desires To MAKE 4 Vsnny ,, u,
which 10 ascertain t,r Sp W ,h c p $3.50 AZ
the number of seconds In an hour are 10 oooo ~
so arr the number Of seconds IN IN" ume snSs VO W.
her Of tcct in each unit Of measurement marked o.,
on the loeno. II hafmnuie 90 sec.hasl La
from each other. and the number Of u,c hlo's 4,
pass from the reel over The stern while ne Sa.u :,
running from the top bulb IN the lower bulo OF ms
cla.s is euua 10 the number ~ knot, or nauucI mis
that the vessel would make IN an houT PRIV s,as =,
.qmo conditions for speed continue Tor ls.ancr, -
The engines steamship continue to make me sals
speed during The hour or II the force Oh W.nu ana
,nroat OF canvass Of sailing vessel continue te salne
ne number Of knots the Inc passing from we reei
While the sand is running through he 30-Secon1 gas,
l. a. ond an oriuql measurement Of the veSSes spetSt
t,rousl the water as coui be obtained except Ina.
The rorr,e should be- measured by an actual survey
VII, tnst~lmcntS II Il was shown that the vessel
was making Ten knots, she would cover ten eeosraps,ca
mil IS or n little more than II IL lana niS, OF
ond n half fines ESQ ,j2-O feet being eIINy,ii,liie
"a land Milo Hence 10 speak Of the CIV OK farl'
having made % knots nautical mi.eS IN - i'oA,s
cha c1vrrs 4 distance 81 Coz IL land nj q. Il, com
nv hendcd ln railroad distances. or rate OF - al,t
mites an hour which Is faster than many fanioHd
trains travel.