Omaha daily bee., 1897-01-02
HOW MUCH is A KNOTT
Few LnnJsmcn Know Its value EN
prNssCd In NIfIra

/
| In this day OF record breaking by oceai
steamers when every big steamer tha
comes into port is expected to carry a rccort
hung at yardarm, so to speak. how many
landsmen know the meaning OF she tern
knot" in which rate OF speed at sea i.
chiefly expressed? 1t is purely and wholly
a nautical term says the New York Her,
aid, having specific application to the speed
! and distance made by a vessel moving in
| the water.
! The word knot Is the mariners term for
nautical mile, and its use is really de.
rived from the log line used by navigators
! OF the ocean when they wish to determine
! the speed aud the distance that the ship
| has probably sailed in n given time. The
! log line Is an important and n very ncces-
| sary part of a ships fittings especially is
| this the case when, for several days at
| sea, the navigator is enabled, because Of the
| sun being hidden by clouds or thick weather
! TO get peep at II with his seXtant,
! from which the actual position OF the ship
! is worked out With the data taken by a
frequent heavlng of the log a small block
! or section of wood with a long line at
| tached and run out from the stern Of the
! vessel for a specific number of sccunds)
! noting the force and direction of the wind,
| the possible currents, or other influences
acting fayorably or against the progress of
! tho ship, the navigator is enabled to calcu-
| late very nearly, In overcast or foggy
| weather. about where his ship is at any
hour Of the day. This is called working
out the position Of the ship by dead reck-
oning"
Every cne who studied the geographical
| table in his early school days will recall
that part OF the sing-song recitation run
ming like this: "Sixty-nne and onc-sixth
statute miles or sixty geographical miles,
equal one degree of longitude at the equator"
hn 4 h.N, a.,
and a nautical or geographical mile is that
the latter is about SOC feet greater than the
| former There are sixty geographical miles
to each degree of latitude, or to each degree
of longitude at the equator, which divisions
of miles are called minutes" in the nautical
vocabulary. hence the old saying "a mile
a minute" As there are 800 degrees or
meridlans. OF longitude, there are 81 coo min
utes, or miles. in the entire circumference
OF the world, at the equator. and II has been
mathematically determined that one minute
ono geographical mile--at the equatorial
circle is equal to 60S6.7 feet. But it has
been the practice Of mariners not to be too
exact on small fractions when measuring a
distance as great as a mile, consequently
the practice of defining a knot or nautical
mile as equal to $3.50 feet instead of 6,0S6.7
feet, has been generally adopted.
When the navigator desires to make log
line by which to ascertain the speed which
his vessel Is making through the water he
follows the constant $3.50 As the num-
Der 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.
If a half-mnute Chirty seconls) glass is to
be used, the knots must he made fifty feet
eight inches from each other and the num-
Der 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
hour, or II the force Of wind and spread OF
canvas of a sailing vessel continue the same,
the number 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, eX
cept that the course should be measured by
an actual survey with Instruments. If II was
shown that the vessel was making ten knots,
she would cover ten geographical miles, or
a little more than eleven and one-half land
miles or eleven and half times $3.50 (5,2S0
feet being equivalent to a land mile). Hence,
to speak OF the City of Paris having made
525 knots or nautical miles in twenty-four
hours, she covers a distance of G0ih land
miles. as comprehended in railroad distances,
or rate of twenty-five land miles an hour,
which Is faster than many railroad trains
travel.