Vermont phÅ“nix. [volume] (Brattleboro, Vt.) 1834-1955, 1895-01-11
Il" HOW TO GET THERE"
Commander Browns Profession
al Club Paper

tgatOrs Find their Way Across the
Great Waters.
The first meeting of the Brattleboro
Professional club for the present season
was held at the Brooks House Wednesday
evening. Commander A. d. Brown was
the essayist, giving a paper on GLOW to
get there"
This enigmatical title proved to be the
happily chosen subject of an interesting
and instructive paper on navigation, de-
scribing the various means which are used
in directing vessel from one port to an
other Confidence, which is the first es-
sential quality of a good navigator, and
the mariners compass, were what enabled
Columbus to find his way across the ocean,
but the means at his command would be
deemed totally inadequate at the present
day. He was the first man to find out, as
the record of his voyage shows, that the
north pole is not always pointed out by
the magnetic needle. The variation of the
needle, as it is called, is not constant in
any one place. The magnetism of the earth,
which attracts the needle, appears to be
central at point some distance south of
the north pole, and at point of longitude
which is constantly changing. The change
in Brattleboro has been about degree in
compass in its simplest form-a magnet
lied needle resting on an iron pin so as to
allow it to swing freely in all directions.
This is the form in which the Chinese,
who were the original discoveries of the
needle, still use it for all ordinary naviga-
ton. The essayist described the construc-
tion of modern ships compass, which
consists of a series of thin magnetized
steel bars or plates boun' firmly together:
two of the needles thus built up are put in
a light brass frame, upon which is a circu-
lar piece of cardboard, marked with the
points of the compass, the north and
south line being parallel to the line of the
needles; the frame swings upon a central
pivot, and the whole compass is enclosed in
a copper bowl which is suspended by two
rings, one outside the other and so con
necteL as to keep the bowl and card APP
proXimately horizontal. Inside the bowl,
which is painted white, is a vertical black
line, called the lubbers point. which marks
the direction of the ships head, the line
between the centre of the compass
and the lubber's point being parallel
to the keel. This is what is known as
a dry compass For use when the ship
rolls and pitches violently wet compass
has been devised, in which the card is of
metal and the needles are contained in two
parallel tubes and the whole suspended
upon pivot in a bowl filled with a mix
ture Of alcohol and water.
Besides the variation of the compass
from the true north there is another error
known as deviation, This being the
amount by which the needle differs from
the true magnetic north. This is caused
by the iron used in the construction of
ships. In a wooden ship the deviation is
due to the machinery in the engine room,
but in a modern iron ship the entire hull
becomes magnet, affecting the compass
in very marked degree. Often this eff
feet is so great that it is necessary to raise
the compass on a tripod, sometimes as
much as 30 feet in height, to get it out of
range of the ships magnetism. BY such
appliances, and by the use of tables and
charts of variation and deviation, the diff
ticulties in the way of steering correctly
are overcome.
The use of the lead for finding the
depth of water when approaching shore in
thick weather was next described The
ordinary lead is round. oblong piece of
this metal attached TO small line, with
distances marked by knots or pieces of
cloth, The deep sea lead weighs % to 80
pounds and the line is wound on a reel.
For the modern steamship this process is
too slow and so a sounding machine is
used, in which the line is piano wire
wound on a drum. This pays out so rap
idly that the lead does not drag behind, but
falls at once to the bottom, leaving no ne
cessity for slackening the speed of the yes
sci. The number of revolutions of the
drum shows the depth, which is automat-
ically recorded on the axle. The deep-sea
lead has a cup-like opening in the lower
end in which is brought up a specimen of
the ocean bottom. This is an important
guide when approaching shore or harbor,
and il is by the information gained in this
way that the ocean liners are able to APP
proach the Jersey shore at full speed At
night or during fogs
The speed OF the ship is shown by the
LOG, which, in its primitive form, consists
OF section, called chip, cut ont of
small circular disc of wood. The circular
edge is loaded with lead to keep it upright;
to this small line is attached and the line
wound on a reel. The line is marked with
knots of small cord so placed that when
the log is hove and the chip falls into the
water the number of knots run out in
given time will indicate the speed-the
| length of line between each knot being the
!
/ pied in running out is of an hour. The
modern steamboat uses a patent log of in
geniOus mechanical construction.
After describing the charts and maps
used by navigators Commander Brown
said; with the chart, log, lead, compass,
and good lookout, aided by a book on nav
/ igaton in which certain tables are all avs
| TO be found, ii is possible, though not al
| ways pleasant, to find the Way from one
/ port to another. Briefly the method is
/ this: Each course steered and the dis
/ tances made are noted on the log slate AT
the end of the day, which for the naviga-
tor is noon, these different courses and dis
tances are set down, and after allowance
has been made for the variation and devia-
| tion OF the compass, the correct course is
/ found; with this and the distance the true
amount of latitude and longitude made
can be found, and this being done for the
several courses of the "a hours the whole
amount of change in position can be as
certained; this being put into conjunction
with the position of the day before the po-
sition at noon is found and plated on the
chart. To illustrate: Suppose one starts
from Brattleboro and goes to Greenfield,
thence to North Adams, thence TO Pitts
field; keeping account of the miles run
and the general direction, the navigator's
tables would tell him how far south or
west he had gone in each case, and from
this the relative location of Pittsfeld from
Brattleboro. This method of navi-
CATION in called dead reckoning in distinc-
ton from that by observation"
The method of taking observations at
sea, the instruments used, and the use of