Peninsula enterprise. [volume] (Accomac, Va.) 1881-1965, 1897-08-28
NILES AND KNOTS.
Some Nautical Information That Is Well
WORTH Remembering.

Worth Remembering.
Distances ut SEA arc measured IN
miles, Just as they arc on land, but the
specd of ship ut sea--that is, the
number of miles she makes through tho
water in one hour of time-is measured
in knots. There is therefore difference
in the meaning OF the word milo and
"knot." They are no more synonymous
than arc the words distance" and
"speed," 10 which they are correlated.
1t is we'll to bear i'll mind, i'll speaking
or writing of nautical matters, this dis
tinction-yhat mile is unit of dis
tauce, but knot is Il unit of speed.
There are two kinds of miles-a statute
or land mile and y nautical or sea mile.
4 statute mile is $3.50 feet long. 1t
is our standard OF itinerary measure
adopted from the English, who i'll turn
adopted it from the Romans. A Roman
military pace, by which distances were
measured, Was the length of the step
taken by the Roman soldiers and was
approximately feet long. y thousand
of these PAGES were called in Latin
mile. The English mile is, therefore,
purely arbitrary measure, enacted into
n legal measure by a statute passed dur
ING the reign of Queen Elizabeth. 1t
has 10 connection with any scale i'll
nature.
\ nautical mile, Oh the other hand,
is equal III length to one-sixtieth part
Of the length of degree of a great cir
Gle Of the earth. But the circumference
of the earth is nowhere Il true circle. It's
radius of curvature is variable. Hence
the nautical mile, rs a matter of fact,
depends for its length upon the shape as
well us the size of the globe sailed over,
and hence, strictly speaking, the length
Of the nautical mile should vary with
the latitude, from 6,046 feet ut the
equator to G,109 feet at the pole.
Such extreme accuracy is not neces-
sary in navigating and cannot be well
attained without undue labor. The Eng
lisll admiralty, therefore, has adopted
1850 feet as the length of nautical
mile, which corresponds with tho length
of one-sixtieth of 4 degree, or one min
ute Of arc OF Il great circle i'll latitude
Is degrees. The united coast survey has
adopted the value Of the nautical mile
las equal TO one-sixtieth part of the
length of Il degree on the great circle of
a sphere whose surface is equal to the
surface Of the earth. y
This gives the length of one nautical
mile as equal TO G, OS0.27 feet, which is
very nearly the value Of the admiralty
mile adopted i'll the English navy.
Practically the nautical mile is 500 feet
longer than the statute mile. In other
words, one nautical mile is equal to
l.15l5 statute miles. or ono statute
mile is equal 10 DISCO nautical mile.
Multiply nautical miles by lob and
the product will be statute miles, or
multiply statute miles by 0.S69, and
the product will be nautical miles.
\ knot is il length nautical mile
that is, &, 0S0 feet. But it never, cor
rectly speaking, means anything more
or less than Il nautical mile an hour.
When saying that ship has Il speed Of
~ knOtS, IL EpiiiiS tilitt III uAe HUI VI
time she can GO 20 nautical miles, pre-
ciselv III tie way that a 2:40 horse
means that horse in minutes and 20
seconds of time can trot one mile. Re-
member, then, that it is erroneous to
use knot as Synonymous with mile; so,
too, is it III error TO say so many knots
AL hour-for the word knots alone sig
nities the time rs we'll as the rate Of
progress of the ship during the time.
Another point to bear i'll mind Is that
though the measure of distance ut sea is
called, ike the measure Of distance on
land, a mile, yet distances at sea are
always measured in nautical miles,
never in statpte miles, and i'll both cases
the single word mile is significant
enough 10 convey the intended meaning.
To say that the distance from New
York to Southampton is 5000 sea or
nautical miles it pathological, but it
would be worse still to say, as many
often do, that the distance is 5000
knots. -Iarper's Round Table.