The state herald., 1897-02-19
HOW MUCH is A KNOTT
Few Landsme Know its Value Expresss
In Miles,

Few Lnndsme Know its Value Expresss
In Miles.
In this day of record breaking by
ocean steamers, when every big steam
er that comes into port Is expected to
carry record hung at yardarm, 30
to speak, how many landsmen know
the meaning of the term knot" In
which rate of speed at sea Is chiefly
expressed? 1t is purely and wholly II
nautical term. having specific appllca-
ton to the speed and distance made by
a vessel moving in the water, says the
New York Herald.
The word knot is the mariners
term for nautical mile, and Its use Is
really derived from the log line used
by navigators of the ocean when they
wish to determine the speed and the
distance that the ship has probably
sailed In n given time. The log line
is an important and very necessary
part of ships fittings; especially IL
this the case when, for several days at
sea, the navigator Is unable. because
of the sun being hidden by clouds or
thick weather, to get Il peep ut 1t with
his sextant, from which the actual po-
sltion Of the ship is worked out. with
the data taken by n frequent hcaviny
wood with a long line attached and
run out from the stern of the vessel for
specific number of seconds) noting
the force and direction of the wind, the
possible currents, or other influences
acting favorably or against the prog
ress of the ship, the navigator is en-
abled to calculate very nearly, In over
cast or foggy weather, about where his
ship Is at any hour of the day. Inis Is
called working out the position of the
ship by dead reckoning"
Every one who studied the geograph-
ical table In his early school days will
recall that part Of the sing-song recita-
tion running like this "Sixty-nine and
one-sixth statute miles, or sixty geo.
graphical miles, equal one degree Of
longitude at the equator" Now, the diff
ference between a statute mile and a
nautical or geographical mile, is that
tie latter Is about S06 feet greater than
the former. There are sixty geograph-
ical miles to each degree of latitude, or
to each degree of longitude at the equa-
tor, which divisions of miles are called
minutes" In the nautical vocabulary.
hence the old saying. IA mile a min
ute" As there are 800 degrees, or me-
ridians, of longitude, there are 81 900
minutes, or miles, In the entire circum-
ference OF the world, at the equator;
and 1t has ben mathematically deter
mined that one minute-one geograph-
icnl mile-at the equatorial circle Is
equal to 6,OS6.I feet. But 1t has been
the practice of mariners not to be too
exact on small fractions when measur-
Ing distance as great rs Il mile, conse
quently the practice of defining knot
or nautical mile as equal TO 6,0S0 feet,
instead OF 6.0SG.7 feet. has been gen
orally adopted.
When the navigator desires to make
log-llne by which to ascertain the
speed which his vessel Is making
through the water he follows the con.
slant 6,OS0. As the number of seconds
In an hour are to 6,OS0 feet, so are the
number of seconds In the time glass tic
be used for measuring the ships speed
to the number of feet In each unit OF
measurement marked OFF on the log.
line If halfminute Thirty seconds
glass Is to be used, the knots must be
made fifty feet eight inches from each
other, and the number of these knots
which pass from the reel over the
stern while the sand is running from
the top bulb to the lower bulb of the
glass Is equal To the number OF knots
or nautical miles that the vessel would
make in an hour, providing the same
conditions for speed continue.
For instance. If the engines OF
steamship continue To make the same
speed during the hour. or II the force
OF wind aud spread of canvas OF a sail.
Ing vessel continue the same. tho num-
Der OF knots ON the line passing from
the reel while the sand is running
through the thirty-second glass Is as
good an actual measurement of the
vessels speed through the water as
could be obtained, except that the
course should he measured by an act
ual survey with Instruments. II It was
shown that the vessel was making ten
knots. she would cover ten geograph-
ical miles, or a little more than eleven
and one-half land miles. or eleven and
half times $50 l5,2SO feet being
equivalent to n land mile, Hence, to
speak Of the City of Paris having made
b25 knots of nautical miles In twenty
four hours, she covers Il distance of
Dlls land miles, as comprehended In
railroad distances, or n rate of twenty
live land miles AN hour. which IL faster
than most railroad trains travel.