The Appeal. [volume] (Saint Paul, Minn. ;) 1889-19??, 1897-09-11
MILES AND KNOTS.
Some Information That Is Well Worth
Remembering.

Some Information That Is Well Worth
Remembering.
Distances at sea are measured in
miles, just as they are on land. but
the speed Of ship at sea-that is, the
number of miles she makes through
the water in one hour of time-is
measured in knots. There is there
fore difference in the meaning Of the
word "mile' and "knot;" they are no
more synonymous than are the words
distance" and "speed," to which they
the correlated. It is we'll to bear in
mlnd' in speaking or writing Of nauti-
cal matters, this distinction, that
mile is a unit of distance, but knot
is unit of speed. There are two
kinds of mile-a statute or land mile
and nautical or sea mile. A statute
mile is $3.50 feet It is our standard
or itinerary measure adopted from the
English, who in 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, a I'd was approximate
~ five feet long; thousand of these
PAGES were called in Latin mile. The
English mile is therefore a purely ar
Dltrary measure, enacted into a legal
measure by statute passed during the
reign OF Queen Elizabeth; it has no
connection with any scale in nature.
n nautical mile, on the other hand, is
equal in length to one-sixtieth part of
the length Of degree of a great circle
or the earth. But the circumference
CT the earth is nowhere a true circle;
It's radius of curvature is variable;
hence the nautical mile, as a matter Of
1act' depends for it's length upon the
shape as we'll as the size of the globe
sailed over; and hence, strictly speak,
lng' the length of the nautical mile
should vary with the latitude, from
o'o46 feet at the equator to 6,1O9 feet
at the pole. Such extreme accuracy is
not necessary in navigating, and can
not be well attained without undue
labor. The English Admiralty, there
lore, have adopted $3.50 feet as the
length OF nautical mile, which CORE
sponds with the length of one-sixtioth
OF degree-or one minute of arc-of
a great circle in latitude 48 degrees.
The United States coast sur
vey has adopted the value of
the nautical mile "as equal
to one-sixtieth part of the length of a
degree on the great circle of a sphere
whose surface is equal to the surface
OF the EARTH" This gives the length
OF one nautical mile as equal to 6,OSO27
feet, which is very nearly the value of
the Admiralty mile adopted in che
English navy. Practically the nauci-
cal mile is 800 feet longer than the
statute mile, In other words, one nau-
tlcal mile is equal to 1.1515 statute miles
or one statute mile is equal to O.s69
nautical mile. Multiply nautical miles
oy 1.l5l5 and the product will be stat
ute miles; or, multiply statute miles
by O.S69, and the product will be mad
tlcal miles. A knot is in length a
nautical mile-that is, $3.50 feet. But
1t never, correctly speaking, means
anything more or less than a nautical
mile an hour. When saying that a
snip has speed of twenty knots, it
means that in one hour of time she
can go twenty nautical miles, precise
1y In the way that a 2:4O horse means
mat horse in two minutes and forty
seconds of time can trot one mile. Re-
member, then, that it is erroneous to
use knot as synonymous with mile:
so, too, it is an error to say so many
knots an hour-for the word knots
alone signifies the time as we'll as the
rate of progress Of the ship during the
time. Another point to bear in mind
is that though the measure at sea is
called, like the measure of distance
on land, mile, like distances at sea
are always measured in nautical miles,
never in statute miles; and in both
cases the single word mile is signifi-
cant enough to convey the intended
meaning. To say that the distance
from New York to Southampton is
5000 sea or nautical miles is tautologi-
cal, but it would be worse still to saw.
as many often do, that the distance is
5000 knots.-Harper's Round Table.