The Colfax chronicle. [volume] (Colfax, Grant Parish, La.) 1877-1981, 1897-03-06
KNOTS AND MILES.
Difference Between Them Explained foa
the BENEFIT Of Landsmen.

Difference Between Them Explained Ton
the BENEFIT Of Landsmen.
In this day of record-breakiDg BY
ocean steamers, when every big steau-
er that comes into port is expected to
carry record hung at a yardarm, so 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 nautical term.
having specific application to the speed
and distance made by vessel moving
In the water.
The word ''knot' is the mariners
term for nautical mile, and its use il
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
given time. The log line is an inn
portant and a very necessary part OF
the ships fittings. Especially is this
the case when, for several days at sea,
the navigator is unable, because of the
sun being hidden by the clouds or thick
weather, to get peep at it with his sex
tant, from which the actual position OF
the ship is worked out. With the data
taken by frequent heaving OF the log
IA small block or section of wood with
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 ia
vorably or against the progress of the
ship, the navigator is enabled to cal.
culate very nearly. in overcast or foggy
weather, about where his ship is at any
hour of the day. This is called "work-
ing out the position of the ship by dead
reckoning"
Everyone who studied the geograph.
zeal table in the early school dayswill re-
call that part of the sing-song recita.
ton running like this: "Sixty-nino
and one-sixth statute miles, or sixty ge-
ographical 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
the latter is about SOC feet greater than
the former. There are 60 geographical
miles to each degree of latitude, or to
each degee of longitude at the equator,
which divisions of miles are called
minutes" in the nautical vocabulary,
hence the old saying, "a mile min
ute." AS there are 800 degrees, OF
meridians, of longitude, there are d.
GOO minutes, or miles, in the entire cir
conference of the world at the equator;
and it has been automatically de-
termined that one minute-one geo.
graphical mile-at the equatorial cir
Gle is equal to 6,0s6.7 feet. But it has
been the practice of mariners not to
be too exact on small fractions when
measuring distance as great as mile,
consequently the practice of defining
u knot or nautical mile as equal to 6,0S0
feet, instead of 6,0s6.7 feet, has been
generally adopted.
When the navigator desires to make
a logline by which to ascertain the
speed which his vessel is making
through the water, he follows the con.
slant $3.50. AS the number of seconds
in an hour are to $3.50 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. IT half minute go seconds)
glass is to be used, the knots must be
made so feet 8 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, IL the engines of a
steamship continue to make the same
speed during the hour, or if the force Of
wind and spread of canvas of a sailing
vessel continue the same, the numbsr Of
knots on the line passing from the reel
while the sand is running through the
3o-secopd glass is as good an ACTUAL
measurement of the vessels speed
through the water as could be obtained,
except that the course should be meas
ured by an actual survey with instru-
ments. If it was shown that the vessel
was making ten knots, she would cover
ten geographical miles, or little more
than 11H land miles, or liz times
$3.50 $3.50 feet being equivalent to a
land mile). Hence, to speak of the
City of Paris having made SIS knots or
nautical miles in "a hours, she covers q
distance of 6O4H land miles, as CON-
pretended in railroad distances, or a
rate of IS land miles an hour, which il
faster than many railroad trains travel.
IN. Y. Herald.