The indicator., 1897-02-20
HOW MUCH is A KNOTT
Few Lnndsms, Know its Value Ezpr s~ss
in Miles,

Few L.ndsms, Know it- Value Ezpr s~ss
In Miles.
In this day of record breaking by
ocean steamers, when every big steam
er that comes into port Is expected TO
carry a record hung at ynrdarm, 10
to speak, how many landsInen know
the meaning of the term Knot, In
which rate of speed Mt sea is chiefly
expressed? 1t is purely and wholly
nautical term. having specific appiica-
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 n nautical mile, and its use is
really derived from the log line used
by nayigators of the ocean when they
wish to determine the speed and the
distance that the ship has probably
sailed in Il given time. The log ilnc
is an important and very necessary
part of ships fittings; especially is
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 peep at 1t with
his sextant, from which the actual po-
sition of the ship is worked out. with
the data taken by II frequent hcaving
| VI lue loE III plb'h VI H'N'i'h VI
wood with n long line attached ami
run out from the stern of the vessel for
| specific number of soconds) 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 In 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. of sixty geo
graphical miles, equal one degree OF
longitude at the equator" Now, the diff
ference between n statute mile and
nautical or geographical mile, Is that
tie latter is about SOC 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 3G0 degrees, or me-
ridians. of longitude, there are q, 800
minutes, or miles. in the entire circum-
and 1t has ben mathematically deter
mined that one minute-one geograph-
ical mile-at the equatorial circle Is
equal to 6,0S61 feet But 1t has been
the practice of mariners not to be too
exact on small fractions when measur-
ing distance as great as a mile, conse-
quently the practice of defining knot
or nautical mile as equal to 6,0S0 feet,
instead of GOSG.T feet, has been gen
orally adopted.
When the navigator desires to make
log-line by which to ascertain the
speed which his vessel is making
through the water. lie follows the con
stant 6,0SO. As the number of seconds
in an hour are to G,OsO feet, so are the
number of seconds in the time glass Ito
be used for measuring the ships speed
to the number of feet in each unit of
! measurement marked off on the log
line. If a half-minute dhirty 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 If the force
of wind and spread of canvas of sail
Ing vessel continue the same, the 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 th
vessels speed through the water as
could be obtained, except that the
course should be measured by an act
ual survey with Instruments If II was
shown that the vessel was making ten
knots, she would cover ten geograph-
fcal miles, or a little more than eleven
and one-half land miles, or eleven and
half times 2,2S0 5,2s0 feet being
equivalent to a land mile. Hence, to
speak of the City of Paris having made
525 knots of nautical miles in twenty
four hours, she covers n distance Of
6O41a land miles. as comprehended in
railroad distances, or n rate of twenty
five land miles an hour, which is faster
than most railroad trains travel.