particularly necessary to point out the errors contained therein[56].
There is evidently too little distance between the lines of no
variation, of which one crosses the equator 17° westward of London, and
the other 119° to the eastward. This makes 136 degrees only; whereas it
should necessarily exceed 180 and even 200, inasmuch as the pole of the
world is supposed farther distant from the magnetic pole towards the
south than in the north, as is required by the other phænomena. Again,
upon the coasts discovered by _Diemen_, there was no variation in 1642;
and Dr. Halley also supposes there was none in 1700. Meanwhile, by the
alteration observed at Paris, the line of no variation should be
advanced 60° towards the south, which will agree better with the
calculations, and prove that the distance of the two intersections was
really greater than Dr. Halley had established.
The table of variation of Mess. Mountaine and Dodson is accompanied with
several interesting particulars, which equally deserve to be inserted
here.
At Barbadoes, (says Capt. Snow) the variation seems very nearly at a
stand; for in the road I observed 5° east; and by Dr. Halley’s draught,
in the year 1701, 5½ degrees. In 1747, at Port Royal keys, Jamaica, I
observed the variation 7° 20´ E.; and on the coast of Carthagena, the
same week, off the high land of Santa Martha, 7° 45´ nearly south of
Port Royal. Therefore these curves are not much altered: the curve at
Jamaica is nearly at a stand, as though tied, and the south part of them
with the rest dropping to the westward.
Under the equator, in longitude 40° E. from London, the highest
variation during the whole fifty-six years appears to be 17°¼ W. and the
least 16°½ W.: and in latitude 15° N. longitude 60° W. from London, the
variation has been constantly 5° E.: but in other places the case has
been widely different. For in the latitude of 10° S. longitude 60° E.
from London, the variation has decreased from 17° W. to 7°¼ W.; and in
latitude 10° S. longitude 5° W. from London, from 2°¼ W. to 12°¾ W.; and
in latitude 15° N. longitude 20°, it has increased from 1° W. to 9° W.
But there is still a more extraordinary appearance in the Indian seas.
For instance, under the equator:
LONGITUDE│ MAGNETICAL VARIATION
East from│ in 1700. in 1756.
London. │
Degrees. │ Degrees. Degrees.
40│ 16¾ West. 16¼ West.
45│ 17¾ W. 14½ W.
50│ 17½ W. 11¾ W.
55│ 16½ W. 8¾ W.
60│ 15¼ W. 6 W.
65│ 13½ W. 4½ W.
70│ 11½ W. 3¼ W.
75│ 9¾ W. 1 W.
80│ 7¾ W. 0¼ East.
85│ 5½ W. 1¼ E.
90│ 4¼ W. 1 E.
95│ 3¼ W. 0½ West.
100│ 2½ W. 1 W.
Where the west variation, in the longitude 40° E. is the same in both
the above years; and in 1700 the west variation seemed to be regularly
decreasing from longitude 50° E. to the longitude 100° E.; but in 1756,
we find the west variation decreasing so fast, that we have east
variation in the longitude 80°, 85°, and 90° E.; and yet in the
longitude 95° and 100° E. we have west variation again. _Philosophical
Transactions for the year 1757._
To these remarks may be subjoined the following extracts from the
_Exposition du calcul astronomique_, by _M. de la Lande_.
At the royal observatory in Paris, a magnetical needle of four inches
deviated from the N. 18° 10´ towards the west, on the 15th of February
1759: and on the 22d of April 1760, the same needle varied 18° 20´. It
is indeed natural to conceive, that nothing can be precisely ascertained
by ten minutes upon a circle whose diameter is only four inches. It is
nevertheless sufficiently evident, that this variation continues to
increase at Paris. In 1610 the needle declined 8° towards the east, so
that the variation has changed 26° 20´ in the space of 150 years; and
this appears particularly since 1740: for the same needle, which has
always been used by M. Maraldi, is more than 3° advanced towards the
west, beyond what it was at that period; and this makes 9´ in one year.
_To_ VEER _and haul_, to pull a rope tight, by drawing it in and
slackening it alternately, till the body to which it is applied acquires
an additional motion, like the increased vibrations of a pendulum, so
that the rope is straitened to a greater tension with more facility and
dispatch. This method is particularly used in hauling the _bowlines_.
The wind is said to veer and haul when it alters its direction, and
becomes more or less _fair_. Thus it is said to veer aft and to haul
forward.
_To_ VEER _away the cable_. See CABLE.
VEERING, _virer vent arriere_, the operation by which a ship, in
changing her course from one board to the other, turns her stern to
windward. Hence it is used in opposition to _tacking_, wherein the head
is turned to the wind, and the stern to _leeward_.
Thus the ship A, fig. 8. plate XI. having made the necessary
dispositions to veer, _bears away_ gradually before the wind, till it
blows obliquely upon the opposite side, which was formerly to leeward,
as at _a_; and as the stern necessarily yields to this impression of the
wind, assisted by the force of the helm, and the action of the waves
upon the same quarter, the side which was formerly to leeward soon
becomes to windward, as in the point _a_.
Since, by this movement, a ship loses ground considerably more than by
tacking, it is rarely practised except in cases of necessity or delay:
as, when the violence of the wind and sea renders tacking impracticable;
or when her course is slackened to wait for a pilot, or some other ship
in company, &c.
It has been observed in the article TACKING, _that the change of motion
in any body, will be in proportion to the moving force impressed, and
made according to the right line in which that force operates_. Hence it
is evident, that veering as well as tacking is a necessary consequence
of the same invariable principle; for as, in the latter, almost the
whole force of the wind and of the helm are exerted on the hind part of
the ship, to turn the prow to windward; so, in the former, the same
impression, assisted by the efforts of the helm, falls upon the prow, to
push it to leeward; and the motion communicated to the ship must in both
cases necessarily conspire with the action of the wind.
Thus, when it becomes necessary to veer the ship, the sails towards the
stern are either furled, or _brailed_ up, and made to _shiver_ in the
wind; whilst those near the head are spread abroad, so as to collect the
whole current of air which their surfaces can contain. Hence, while the
whole force of the wind is exerted on the fore part of the ship to turn
her about, its effect is considerably diminished, or altogether
destroyed, on the surfaces of the after-sails. The fore part accordingly
yields to the above impulse, and is put in motion; and this movement,
conspiring with that of the wind, pushes the ship about as much as is
necessary to produce the effect required. When she is turned so that the
wind will act upon that quarter which was formerly to leeward, as at the
point _a_, fig. 8. her circular motion will be accelerated by extending
some of the sails near the stern, as the mizen, and by placing those at
the prow more obliquely, which will wheel the vessel round with her bow
to the windward; in the same situation, with regard to the wind, as when
_close-hauled_, or tacking.
When the tempest is so violent as to prevent the use of sails, the
effort of the wind operates almost equally on the opposite ends of the
ship, so that the masts and yards situated at the head and stern
counterbalance each other. The effect of the helm is also considerably
diminished, because the _head-way_, which gives life and vigour to all
its operations, is at this time feeble and ineffectual. Hence it is
necessary to defray this equilibrium which subsists between the masts
and yards _afore_ and _abaft_, and to throw the balance forward, in
order to prepare for veering. This is accordingly performed by bracing
the foremost yards across the direction of the wind, and arranging those
on the main-mast and mizen mast directly in the line of the wind. If
this expedient proves unsuccessful, and it is absolutely necessary to
veer, in order to save the ship from destruction, by oversetting or
running ashore, the mizen-mast must instantly be cut away, and even the
main-mast, if she yet remains incapable of answering the helm by bearing
away before the wind.
VENT. See the articles _Cannon_ and _Windage_.
VESSEL, _batiment_, a general name given to the different sorts of ships
which are navigated on the ocean, or in canals and rivers. It is,
however, more particularly applied to those of the smaller kind,
furnished with one or two masts.
It has already been remarked in the article SHIP, that the views of
utility, which ought always to be considered in a work of this kind,
seemed to limit our general account of shipping to those which are most
frequently employed in European navigation. We have therefore collected
into one point of view the principal of these in plate XII.; so that the
reader who is unacquainted with marine affairs, may the more easily
perceive their distinguishing characters, which are also more
particularly described under the reflective articles.
Thus fig. 4. plate XII. exhibits a snow under sail; fig. 5. represents a
ketch at anchor; fig. 6. a brig or brigantine; fig. 7. a bilander; fig.
8. a xebec; fig. 9. a schooner; fig. 10. a galliot; fig. 11. a dogger;
all of which are under sail; fig. 12. & 13. two galleys, one of which is
under sail, and the other rowing; and fig. 14. a sloop.
The ketch, whose sails are furled, is furnished with a try-sail, like
the snow; and it has a fore-sail, fore-staysail, and jib, nearly similar
to those of a sloop; but the sails on the main-mast and mizen-mast are
like those of a ship. The main-sail and main-topsail of the brig are
like those of the schooner; and the fore-mast is rigged and equipped
with sails in the same manner as the ship and snow. The sails, masts,
and yards of the xebec, being extremely different from these, are
described at large under the article. In the schooner both the mainsail
and foresail are extended by a _boom_ and _gaff_, as likewise is the
sloop’s mainsail; the sails of the dogger and galliot are sufficiently
expressed in the plate; and, finally, the galleys are navigated with
lateen-sails, which are extremely different from those of the vessels
above described.
_Agent_ VICTUALLER. See AGENT VICTUALLER.
_To_ UNBALLAST, _delester_, to discharge the ballast of a ship.
UNBENDING, _désamarrer_, generally implies the act of taking off the
sails from their yards and stays; of casting loose the anchors from
their cables, or of untying one rope from another. See also _Bend_.
UNBITTING, _débitter_, the operation of removing the turns of a cable
from off the bits. See BITS and CABLE.
_To_ UNDER-RUN, _parcourir_, to pass under or examine any part of a
cable or other rope, in order to discover whether it is damaged or
intangled.
It is usual to under-run the cables in particular harbours, as well to
cleanse them with brooms and brushes from any filth, ooze, shells, &c.
collected in the stream; as to examine whether they have sustained any
injury under the surface of the water; as, from rocky ground, or by the
friction against other cables or anchors.
[Illustration:
_PLATE. XII_ _to face VESSEL_
]
_To_ UNDER-RUN _a tackle_, is to separate the several parts of which it
is composed, and range them in order, from one block to the other; so
that the general effort may not be interrupted, when it is put in
motion.
UNDER SAIL, the state of a ship when she is loosened from her moorings,
and under the government of her sails and rudder. See HELM and SAIL.
UNLACING, _déboutonner_, the act of loosening and taking off the
_bonnet_ of a sail from its principal part.
_To_ UNMOOR, _desafourcher_, is to reduce a ship to the state of
_riding_ by a single anchor and cable, after she has been _moored_ or
fastened by two or more cables. See the articles ANCHOR and MOORING.
UNREEVING, the act of withdrawing or taking out a rope from any channel
through which it had formerly passed; as in a _block_, _thimble_,
_dead-eye_, &c. See REEVE.
_To_ UNRIG _a ship_, _défuner_, is to deprive her of the standing and
running _rigging_.
VOYAL, _tournevire_, a large rope used to unmoor, or heave up the
anchors of a ship, by transmitting the effort of the _capstern_ to the
cables.
This is performed by fastening one part of the voyal to the cable in
several places, and by winding another part thereof three or four times
about the capstern, which answers the same purpose as if the cable
itself were in that manner wound about the capstern; and the voyal being
much lighter and more pliant, is infinitely more convenient in this
exercise. See the articles CAPSTERN and NIPPER.
If the cable is drawn into the ship by the main capstern, the voyal is
used without any block: but if the capstern in the fore-part of the ship
be employed for this purpose, the voyal usually passes through a large
block attached to the main-mast; and thence communicates with the
jear-capstern.
UPPER-DECK, the highest of those decks which are continued throughout
the whole of a ship of war, or merchantman, without any interruption, of
steps or irregular ascents. See DECK and WAIST.
UPPER-WORK, _oeuvres mortes_, a general name given to all that part of a
ship which is above the surface of the water when she is properly
balanced for a sea-voyage: hence it may be considered as separated from
the bottom by the main _wale_, as explained particularly in the article
_Naval_ ARCHITECTURE.
UPRIGHT, the situation wherein the opposite sides of a ship are equally
elevated above the surface of the water, as in fig. 2. plate VI.; or
when she neither inclines to the right nor left, with regard to the
vertical position of her stem and stern-post.
USES AND CUSTOMS _of the sea_; certain general principles which compose
the basis of marine jurisprudence, and regulate the affairs of commerce
and navigation.
W.
WAD, _bourrelet_, a quantity of old rope-yarns rolled firmly together
into the form of a ball, and used to confine the shot or shell, together
with its charge of powder, in the breech of a piece of artillery.
M. Le Blond observes, in his Elements of war, that the wad is necessary
to retain the charge closely in the chamber of the cannon, so that it
may not, when fired, be dilated around the sides of the ball, by its
_windage_ as it passes through the chace; a circumstance which would
considerably diminish the effort of the powder. But as the wad cannot be
fastened to the sides of the bore, it is carried away in the same
instant when the charge is inflamed, and that with so little resistance,
that it cannot in any degree retard the explosion, or give time for the
entire inflammation of the powder.
This reasoning may with equal propriety be applied to the wad that
covers the bullet; which, nevertheless, is absolutely requisite, to
prevent it from rolling out when the piece is fired horizontally or
pointed downwards. Both are therefore peculiarly necessary in naval
engagements, because, without being thus retained in its chamber, the
shot would instantly roll out of the chace by the agitation of the
vessel.
WAFT, _berne_, a signal displayed from the stern of a ship for some
particular purpose, by hoisting the ensign, furled up together into a
long roll, to the head of its staff. It is particularly used to summon
the boats off from the shore to the ship whereto they belong; or as a
signal for a pilot to repair aboard. See SIGNAL.
WAIST, that part of a ship which is contained between the quarter-deck
and fore-castle, being usually a hollow space, with an ascent of several
steps to either of those places.
When the waist of a merchant-ship is only one or two steps of descent
from the quarter-deck and fore-castle, she is said to be galley-built;
but when it is considerably deeper, as with six or seven steps, she is
called frigate-built. See the articles DECK, DEEP-WAISTED, and FRIGATE.
WAKE, _houaiche_, the print or track impressed by the course of a ship
on the surface of the water. It is formed by the re-union of the body of
water, which was separated by the ship’s bottom whilst moving through it
and may be seen to a considerable distance behind the stern, as smoother
than the rest of the sea. Hence it is usually observed by the compass,
to discover the angle of LEE-WAY.
A ship is said to be in the wake, _dans l’eau_, of another, when she
follows her on the same track, or on a line supposed to be formed on the
continuation of her keel. Thus the ships _a_ _b_, fig. 11. and _a_ _b_,
fig. 7. plate V. are all in the wake of the foremost _b_. See the
article LINE.
Two distant objects observed at sea are called in the _wake_ of each
other, when the view of the farthest is intercepted by the nearest; so
that the observer’s eye and the two objects are all placed upon the same
right line.
WALE-KNOT, or WALL-KNOT, a particular sort of large knot raised upon the
end of a rope, by untwisting the _strands_, and interweaving them
amongst each other. See the article KNOT.
WALE-REARED, an obsolete phrase, implying _wall-sided_, which see.
WALES, _preceintes_, an assemblage of strong planks extending along a
ship’s side, throughout her whole length, at different heights, and
serving to reinforce the decks, and form the curves by which the vessel
appears light and graceful on the water.
As the wales are framed of planks broader and thicker than the rest,
they resemble ranges of hoops encircling the sides and _bows_. They are
usually distinguished into the main-wale and the channel-wale; the
breadth and thickness of which are expressed by Q and R in the
MIDSHIP-FRAME, plate VII. and their length is exhibited in the
ELEVATION, plate I. where L Q Z is the main-wale, and D R X the
channel-wale, parallel to the former.
The situation of the wales, being ascertained by no invariable rule, is
generally submitted to the fancy and judgment of the builder. The
position of the gun-ports and scuppers ought, however, to be
particularly considered on this occasion, that the wales may not be
wounded by too many breaches.
WALL-SIDED, the figure of a ship’s side, when, instead of being
incurvated so as to become gradually narrower towards the _upper part_,
it is nearly perpendicular to the surface of the water, like a wall; and
hence the derivation of the phrase.
WALT, an obsolete or spurious term signifying _crank_. See that article.
WARP, a small rope employed occasionally to remove a ship from one place
to another, in a port, road, or river. And hence,
_To_ WARP, _remorquer_, is to change the situation of a ship, by pulling
her from one part of a harbour, &c. to some other, by means of warps,
which are attached to buoys; to anchors sunk in the bottom; or to
certain stations upon the shore, as posts, rings, trees, &c. The ship is
accordingly drawn forwards to those stations, either by pulling on the
warps by hand, or by the application of some purchase, as a tackle,
windlass, or capstern, upon her deck. See those articles.
When this operation is performed by the ship’s lesser anchors, these
machines, together with their warps, are carried out in the boats
alternately towards the place where the ship is endeavouring to arrive:
so that when she is drawn up close to one anchor, the other is carried
out to a competent distance before her, and being sunk, serves to fix
the other warp by which she is farther advanced.
Warping is generally used when the sails are _unbent_, or when they
cannot be successfully employed, which may either arise from the
unfavourable state of the wind, the opposition of the tide, or the
narrow limits of the channel.
WASH. See the article OAR.
WASH-BOARD, a broad thin plank fixed occasionally on the top of a boat’s
side, so as to continue the height thereof, and be removed at pleasure.
It is used to prevent the sea from breaking into the vessel,
particularly when the surface is rough, as in tempestuous weather.
WATCH, _quart_, the space of time wherein one division of a ship’s crew
remains upon deck, to perform the necessary services, whilst the rest
are relieved from duty, either when the vessel is under sail, or at
anchor.
The length of the sea-watch is not equal in the shipping of different
nations. It is always kept four hours by our British seamen, if we
except the _dog_-watch between four and eight in the evening, that
contains two reliefs, each of which are only two hours on deck. The
intent of this is to change the period of the night-watch every
twenty-four hours; so that the party watching from eight till twelve in
one night, shall watch from midnight till four in the morning on the
succeeding one. In France the duration of the watch is extremely
different, being in some places six hours, and in others seven or eight;
and in Turky and Barbary it is usually five or six hours.
A ship’s company is usually classed into two parties; one of which is
called the starboard and the other the larboard watch. It is, however,
occasionally separated into three divisions, as in a _road_ or in
particular voyages.
In a ship of war the watch is generally commanded by a lieutenant, and
in merchant-ships by one of the mates; so that if there are four mates
in the latter, there are two in each watch; the first and third being in
the larboard, and the second and fourth in the starboard watch: but in
the navy the officers who command the watch usually divide themselves
into three parts, in order to lighten their duty.
WATCH-GLASSES, _horloge_, a name given to the glasses employed to
measure the period of the watch, or to divide it into any number of
equal parts, as hours, half-hours, &c. so that the several stations
therein may be regularly kept and relieved; as at the _helm_, _pump_,
_look-out_. &c.
_To set the_ WATCH, is to appoint one division of the crew to enter upon
the duty of the watch; as at eight o’clock in the evening. Hence it is
equivalent to _mounting the guard_ in the army. See the French term
BORDÉE.
WATER-BORNE, the state of a ship, with regard to the water surrounding
her bottom, when there is barely a sufficient depth of it to float her
off from the ground; particularly when she had for some time rested
thereon.
For _Dead_-WATER, _Foul_ WATER, and _High_-WATER, see DEAD, FOUL, and
HIGH.
WATER-LINES, _lignes d’eau_, certain horizontal lines supposed to be
drawn about the outside of a ship’s bottom, close to the surface of the
water in which she floats. They are accordingly higher or lower upon the
bottom, in proportion to the depth of the column of water required to
float her. See a particular account of these in the article _Naval_
ARCHITECTURE.
In order to conceive a clearer idea of the curves of those lines when
represented on a plane, let us suppose a ship laid _upright_ on a level
ground; so that the keel shall lie in the same position, with respect to
the horizon, as when she is laden. We may then describe several black
horizontal lines about her bottom, which may be whitened for that
purpose.
If a spectator is supposed to be placed, at a competent depth, under the
middle of her bottom, in a line perpendicular to the plane of the
ground; he will then, viewing the bottom upwards, discover the
horizontal curves of all the water-lines.
These curves are all delineated on a plane, supposed to be formed by an
horizontal section of the bottom, at the height of the load-water-line,
_ligne d’eau du vaisseau chargé_.
WATER-LOGGED, the state of a ship when, by receiving a great quantity of
water into her hold, by leaking, &c. she has become heavy and inactive
upon the sea, so as to yield without resistance to the efforts of every
wave rushing over her decks. As, in this dangerous situation, the center
of gravity is no longer fixed, but fluctuating from place to place, the
stability of the ship is utterly lost: she is therefore almost totally
deprived of the use of her sails, which would operate to overset her, or
press the head under water. Hence there is no resource for the crew,
except to _free_ her by the pumps, or to abandon her by the boats as
soon as possible.
WATER-SAIL, a small sail spread occasionally under the lower
studding-sail, or driver-boom, in a fair wind, and smooth sea.
WATER-SHOT. See the article MOORING.
WATER-SPOUT, an extraordinary and dangerous meteor, consisting of a
large mass of water, collected into a sort of column by the force of a
whirlwind, and moved with rapidity along the surface of the sea.