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since its use is only occasionally required? Apertures must be made in all the decks to admit of the screw being hoisted up for the purpose of repairing it, or of replacing it by another. In the latter case, the spare propeller (screw) is brought out of the stowagebed in the hold, and transported aft on a suitable sledge. The tackle by which the screw is hoisted consists of a double system of pulleys suspended from a strong timber (chock) spanning the aperture in the upper deck: each fall is made fast at one end to an immoveable object; passing then over a friction-pulley in the chock, it is led under a pulley fixed to the metal frame which carries the screw, and is passed from thence over another friction-pulley in the chock to the barrel of the capstan : by heaving on this the metal frame, with the screw, is raised through the trunk to the upper deck. When the screw is damaged and requires to be replaced or repaired, shears are erected of sufficient altitude to hoist the screw entirely clear of the aperture; the frame with the screw is then lowered to the deck, when what is amiss may be repaired, or the screw may be replaced by a spare one. While this operation is being performed, which is accomplished in ten or twelve minutes after the gearing is prepared, the long tiller cannot, of course, be used; this must, therefore, be unshipped and triced up to the beams, and the yoke or short tiller must be applied for the purpose of steering the ship till the screw is refixed; but it must be unnecessary to enclose the apertures by permanent bulkheads. Might it not suffice to carry the trunk up from the top of the aperture in which the screw works, as high as the lower-deck, and no higher? To prevent the surge of the sea, up the permanent trunk, from getting into the lower deck, a strong cap of timber should be made to close the aperture, the chain attached to the screw being passed through a hole perforated in the centre of the cover, and kept ready to be passed through the apertures in the decks above, when the operation of hoisting the screw is required. When the screw is to be hoisted up, temporary stanchions might be fixed in mortices at the four corners of the rectangular space (a a fig. 6) to which the boss must be confined in moving the screw up and down; and by these stanchions the edges of the metal frame in which the screw is set may, in lowering it, be conducted into the metal guides fixed vertically in the permanent trunk below the lower deck, so as to bring it, as before, to the proper place for connecting the screw with the propelling shaft. By suppressing the trunk, the decks would be free for the movements of a tiller of the ordinary length and description, which, like the yokes, might be placed immediately under the beams of the quarter-deck and main deck respectively: the apertures being covered by shutters, on which guns might be placed, the stern batteries on each deck would be strengthened by the two guns which the trunk had rendered useless; and thus spaces of about 700 and 1000 cubic feet, in two and three deck ships respectively, would be restored to the gun and ward room accommodation, and to the apartments appropriated to the captain and the admiral.
The great advantage of applying screw-propulsion to ships of war consists in these being enabled to execute, with the utmost precision and certainty, the tactical movements which the new system of naval warfare will introduce. But that precision in execution depends entirely upon the accuracy with which the new moving power is directed by ihe helm; and so indispensable is correct steering in the evolutions of steam-fleets, that the full benefit which steam propulsion is capable of affording cannot be obtained without it. The reader will see, in the sequel of this work, the immense importance of steady and correct steering in the evolutions of steam-fleets; and naval officers, in practising the new and delicate manoeuvres of which the author is about to treat, will find that the most serious consequences will result from any defect in the apparatus by which steam-ships are steered.
The steering of a screw steam-ship of the line, with all sails furled, should be as if instinct with life, intuitive, and quick as volition. The more simple and direct the regulating power of the helm is, the more it will conform with the above attributes.
On The Tactics Op Naval Wabfaee With Steam.
80. The tactics of naval warfare under the power of steam cannot be advantageously studied except in comparison with those in which the movements of the ships depend on the action of the wind; and it, therefore, will be necessary to begin by a short description of the elementary principles which have governed the operations of hostile fleets in past times, when the manoeuvring powers of the sail alone could be employed to effect the requisite evolutions. The nature of these evolutions being explained, it is proposed to enter upon a description of the means of executing them, and of the modifications which must be made in the tactics of naval warfare when ships are moved by the power of steam.
81. The science of naval warfare may be classed under two principal divisions :—the order of movement in advance or retreat, and the order of battle.
In 1697 Paul Hoste" published his treatise of Naval Evolutions; and this work, which was reprinted in 1727, is, by all writers on the art, pronounced to be the ground on which succeeding theories have been based.b
82. With respect to the first of these divisions,
* Father Paul l'Hoste, a Jesuit, was born at Bresse in 1652, and died Professor of Mathematics in the Eoyal College of Marine, at Toulon, in 1700, aged 48. He was present in many of the battles he describes, having served for many years with some of the most distinguished admirals of Prance. He was on board the Count de Tourville's ship at the battle of La Hogue in 1692, and served in some of the sanguinary battles fought between the English and Dutch fleets in the 17th century.
b The principal writers on naval tactics since the time of Paul Hoste are:— M. Bourde de Villehuit, 1769; M. de Moroques and M. du Pavilion, 1780; Clarke of Eldon, 1790; Viscomte de Grenier, 1788; Steel, 1794; Admiral Sir Charles Ekins' Naval Battles.
Paul Hoste enumerates six orders of sailing, which are as follow:—
1. The line ahead on the starboard or the port
tack; which is also the general order of battle.
2. The line ahead perpendicular to the wind.
3. On two lines of bearing* when it is not known
on what tack it will be necessary to engage.
4. In parallel columns or divisions before the wind.
5. In parallel columns oblique to the wind.
6. The order of retreat on two lines of bearing,
making with each other an angle of 135°.
83. He afterwards dwells on the derangements which may be occasioned by changes of the wind occurring during an action, and on the manoeuvres by which those changes should be met:—
1. The manner of re-establishing the line of battle
when the wind comes ahead.
2. The manner of re-establishing the first order of
sailing when the wind comes aft.
3. The manner of re-establishing the second order
of sailing when the wind changes.
4. The manner of re-establishing the third and
the fourth orders when the wind changes 16 points, or less than 16 points.
5. The manner of re-establishing the fifth order
when the wind changes 4, 6, 8, or 12 points, and when the wind comes ahead.
6. The manner of re-establishing the order of
retreat when the wind changes 4, 6, 8, 12, or 16 points.
To which he adds the manner of changing the order of battle to the different orders of sailing.
* Two lines of bearing are those in which the ships (at 6 points from the wind) are in lines, making with each other an angle of 135 degrees (see fig. 9, p. 93). From this order of sailing the line of battle can be promptlyformed on either tack; for one portion of the fleet is already in line ahead, and the other may be speedily brought to the same disposition, in the continuation of that line towards the rear.
84. In the tactics of sailing ships, the line of battle is formed by ranging the ships in line ahead, at 6 points from the wind, either on the starboard or the port tack."
It has always been assumed, in preparing for an attack, that the fleet of the enemy is in line ahead closehauled, to leeward or to windward; and by taking measures accordingly, with superior nautical skill and practical seamanship, the officers of the British navy have established and maintained for the country its supremacy on the ocean.
85. The intervals between ships in line of battle are never less than one cable's length, or 240 yards, but they may be at the distance of one and a half or even two cables' length. The ships are close-hauled to the wind, because in that trim the sails are easily made to counteract each other, by backing, filling, or shivering them, and thus the ships are easily kept in their proper stations. This can, with difficulty, be accomplished by the process of bracing-by? when ships are going free, or before the wind.
The line of battle is not formed in a direction perpendicular to the wind, because, when ships so ranged make a tack, there is greater danger of each getting foul of her follower, in falling off upon the new tack, than when the ships are hauled to the wind.
The close-hauled lines form the normal condition upon which line of battle and all orders of sailing in lines of bearing are formed. In this state the conversion from the line of bearing to the line of battle might be simply and promptly made, subject to the limitations imposed by the wind.
86. The attack from the windward upon an enemy's fleet to leeward, is made by running down directly in line abreast, or obliquely in line of bearing,
* These are called in naval tactics close-hauled lines; but square-rigged ships so ranged are one point off the wind.
b The method called bracing-hy consists in turning the yards more or less obliquely to the wind, in order to discharge (spill) the wind from the sails, or to catch it on them, as the occasion may require.