New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1898-09-25
THE SPEED OF A SHIP.
METHODS OF MEASURING 1.-THE USE
OF THE LOG

OF THE LOG.
From The Navy and Army illustrated.
"How do you ascertain the speed OF a vessel!
Is a question frequently addressed 10 naval men,
and an explanation Will therefore probably ne
Of interest 10 many readers. There are several
methods, the commonest and most ancient being
By the use Of the log This instrument consists
of three parasitic IOgShip, the line, ana the
marks. The logshp is piece OF wood about
half an inch thick, and shaped like quadrant,
with a piece OF lead let In round the circular
edge to make ii float perpendicularly IN the
water. II Is slung by lines at each angie the
three lines being joined together about TWO 1eet
from the lOgshp Two Of the lines are securely
fixed to the ship" and the other has a bone
peg at the end, which iying pushed into hole
in the ship temporarily 1astens II there FROM
the point Of juncture Of the three lines snfii-
cient length ig measured. generally about one
hundred feet. to take the logskip well clear of
the ships wash. This is called the stray line.
and ~ marked with a piece OF bunting FROM
the bunting is measured AZ feet 3 inches, and
tn line marked here with a piece OF leather.
Then another ~ feet 3 inches is measured off,
and marked with two knots then another space
the same length, and marked with three KNOTS
and SO on as far as seven knots Halfway be-
tween each batch OF knots one single Knot Is
made. The logne is .hen ready Tor use
The space between the knots is found from
the simple little rule-of-threo sum: As o"dh sec
q dis number Of seconds IN an hour, = seconds
deneth Of sandglass), C.0So feet number of feet
in a nautical mile. length OF line required
which works out to ~ feet 3 inches.
To use the log four persons are required two
men 10 hold :he reel on which The line Is wound:
the QuarterInastcr. to hold the glass; and the
midshiprnan Of the watch, to heave the log The
last named puts the peg firmly H. the Iogship'
and then gathers three or four coils OF line IN
/ his hand. sufhC tent O. admit OF the irgShlI be-
| ing thrown well clear Of the snip. lie asks.
Clear glass. quartermaster"' Clear glass
sir the reply. and overheard goes the
lofship and line. the reel rapidly revolving.
Presently Tho mildly feels the piece of bunting
passing through his hand. and he gives the
order. Turn" The quartermaster turns the
glass. ana watches the sand while one "reeler
! holds the reel well over his head So as to give
| the line iair play. When the sand has run out.
| stop cries the quartcrmaster. The midship-
grasps The line. assisted 10y the other rceier.
and looks FOR thu nearest knot, finding single
one clos, a. his hand Then the line IS hauled
/ in. and four knots appear which SIGNIFY thar
/ the ship is going four and half knots through
/ the water The jerk OF the line draws the peg
/ from the logship. which now floats on It's fat
side and is easily hauled IN. when snip is
going over four knots. fourteen-second glass
is used the speed being double that shown by
the knots the line
Another method in use is the patent log This
/ is alfoccthcr mec meal and consists of a long
! cylinder with clockwork inside IT, and four fms
on tn outside. II Is flowed astern Of the ship
ly q line made fast 10 swivel IL the head Of
b. A. B; D. dragged through the water the four
D hns make II reNulve. aCtuLtnC the clockW0rK
. inside. which registers on "A series OF diaIs the
number ~ knots run. This log has L. be hauled
/ In every t.m- one wants O. read IT, Hut there
and the dial ~ fixture IL the ship. This IS
called :. "cheruh
Thoso logs are not always accurate. and are
constantly verified when near land 10y cross
bearings THAT is TIA bearings Of two WE'LL
known points ar" taken and the position So OBJ
taiucc rs marked on the chart. thu time %. OBJ
s.rvation being noted. and the reading the
patent log After an interval has elapsed. the
position II tie ship Is again taken 10y cross
bearings when tho straight line joining the
tWU places tho chart Will show the direction
- IA" course gtcrrcd, and It's length the dis
tauce ruu. comparison with the readings by
patent log will give the error Of tn" machine
r finish here i "A patent log yarn. as told
hy an I'D W'ssmatc ] give II N ms own words
. When 10 tho Crocodile IN the Rec Sea Just
after taking Tho reading one night al o'clock
tho qUartcrfuaSter reported shark taken The
patent Jog sir" got another one over at once
/ At $50 uoNt morning We stopped for half an
J. hour p amuso the ladies ! tried Tor and
. caught shark on opening him we found our
J. patent log. and n added graVcly. strange 10
/ say. u registered the same the one in The
/ line had TANNED between his teeth The fan
working all the time he followed the ship. lie
had swum just - 10 miles