Part 29 (1/2)
The modern steams.h.i.+p is as wonderful an ill.u.s.tration of ingenuity and skill in all interior arrangements as in size, power, and speed. The size of sea-going steamers has become so great that it is unsafe to intrust the raising of the anchor or the steering of the vessel to manual power and skill; and these operations, as well as the loading and unloading of the vessel, are now the work of the same great motor--steam.
The now common form of auxiliary engine for controlling the helm is one of the inventions of the American engineer F. E. Sickels, who devised the ”Sickels cut-off,” and was first invented about 1850. It was exhibited at London at the International Exhibition of 1851. It consists[98] princ.i.p.ally of two cylinders working at right angles upon a shaft geared into a large wheel fastened by a friction-plate lined with wood, and set by a screw to any desired pressure on the steering-apparatus. The wheel turned by the steersman is connected with the valve-gear of the cylinders, so that the steam, or other motor, will move the rudder precisely as the helmsman moves the wheel adjusting the steam-valves. This wheel thus becomes the steering-wheel. The apparatus is usually so arranged that it may be connected or disconnected in an instant, and hand-steering adopted if the smoothness of the sea and the low speed of the vessel make it desirable or convenient. This method was first adopted in the United States on the steams.h.i.+p Augusta.
[98] ”Official Catalogue,” 1862, vol. iv., Cla.s.s viii., p. 123.
The same inventor and others have contrived ”steam-windla.s.ses,” some of which are in general use on large vessels. The machinery of these vessels is also often fitted with a steam ”reversing-gear,” by means of which the engines are as easily man[oe]uvred as are those of the smallest vessels, to which hand-gear is always fitted. In one of these little auxiliary engines, as devised by the author, a small handle being adjusted to a marked position, as to the point marked ”stop” on an index-plate, the auxiliary engine at once starts, throws the valve-gear into the proper position--as, if a link-motion, into ”middle-gear”--thus stopping the large engines, and then it itself stops. Setting the handle so that its pointer shall point to ”ahead,”
the little engine starts again, sets the link in position to go ahead, thus starting the large engines, and again stops itself. If set at ”back,” the same series of operations occurs, leaving the main engines backing and the little ”reversing engine” stopped. A number of forms of reversing engine are in use, each adapted to some one type of engine.
The hull of the transatlantic steamer is now always of iron, and is divided into a number of ”compartments,” each of which is water-tight and separated from the adjacent compartments by iron ”bulkheads,” in which are fitted doors which, when closed, are also water-tight. In some cases these doors close automatically when the water rises in the vessel, thus confining it to the leaking portion.
Thus we have already seen a change in transoceanic lines from steamers like the Great Western (1837), 212 feet in length, of 35-1/2 feet beam, and 23 feet depth, driven by engines of 450 horse-power, and requiring 15 days to cross the Atlantic, to steams.h.i.+ps over 550 feet long, 55 feet beam, and 55 feet deep, with engines of 10,000 horse-power, crossing the Atlantic in 7 days; iron subst.i.tuted for wood in construction, the cost of fuel reduced one-half, and the speed raised from 8 to 18 knots and over. In the earlier days of steams.h.i.+ps they were given a proportion of length to breadth of from 5 to 6 to 1; in forty years the proportion increased until 11 to 1 was reached.
The whole naval establishment of every country has been greatly modified by the recent changes in methods of attack and defense; but the several cla.s.ses of s.h.i.+ps which still form the naval marine are all as dependent upon their steam-machinery as ever.
[Ill.u.s.tration: H. B. M. Iron-Clad Captain. H. B. M. Iron-Clad Thunderer. U. S. Iron-Clad Dictator. U. S. Iron-Clad Monitor. H. B. M.
Iron-Clad Giatton. French Iron-Clad Dunderberg. FIG. 145.--Modern Iron-Clads.]
It is only recently that the attempt seems to have been made to determine a cla.s.sification of war-vessels and to plan a naval establishment which shall be likely to meet fully the requirements of the immediate future. It has. .h.i.therto been customary simply to make each s.h.i.+p a little stronger, faster, or more powerful to resist or to make attack than was the last. The fact that the direction of progress in naval science and architecture is plainly perceivable, and that upon its study may be based a fair estimate of the character and relative distribution of several cla.s.ses of vessels, seems to have been appreciated by very few.
In the year 1870 the writer proposed[99] a cla.s.sification of vessels other than torpedo-vessels, which has since been also proposed in a somewhat modified form by Mr. J. Scott Russell.[100] The author then remarked that the increase so rapidly occurring in weight of ordnance and of armor, and in speed of war-vessels, would probably soon compel a division of the vessels of every navy into three cla.s.ses of s.h.i.+ps, exclusive of torpedo-vessels, one for general service in time of peace, the others for use only in time of war.
[99] _Journal Franklin Inst.i.tute_, 1870. H. B. M. S. Monarch.
[100] London _Engineering_, 1875.
”The first cla.s.s may consist of unarmored vessels of moderate size, fair speed under steam, armed with a few tolerably heavy guns, and carrying full sail-power.
”The second cla.s.s may be vessels of great speed under steam, unarmored, carrying light batteries and as great spread of canvas as can readily be given them; very much such vessels as the Wampanoag cla.s.s of our own navy were intended to be--calculated expressly to destroy the commerce of an enemy.
”The third cla.s.s may consist of s.h.i.+ps carrying the heaviest possible armor and armament, with strongly-built bows, the most powerful machinery that can be given them, of large coal-carrying capacity, and unenc.u.mbered by sails, everything being made secondary to the one object of obtaining victory in contending with the most powerful of possible opponents. Such vessels could never go to sea singly, but would cruise in couples or in squadrons. It seems hardly doubtful that attempts to combine the qualities of all cla.s.ses in a single vessel, as has. .h.i.therto been done, will be necessarily given up, although the cla.s.sification indicated will certainly tend largely to restrict naval operations.”
The introduction of the stationary, the floating, and the automatic cla.s.ses of torpedoes, and of torpedo-vessels, has now become accomplished, and this element, which it was predicted by Bushnell and by Fulton three-quarters of a century ago would at some future time become important in warfare, is now well recognized by all nations.
How far it may modify future naval establishments cannot be yet confidently stated, but it seems sufficiently evident that the attack, by any navy, of stationary defenses protected by torpedoes is now quite a thing of the past. It may be perhaps looked upon as exceedingly probable that torpedo-s.h.i.+ps of very high speed will yet drive all heavily-armored vessels from the ocean, thus completing the historic parallel between the man-in-armor of the middle ages and the armored man-of-war of our own time.[101]
[101] _Vide_ ”Report on Machinery and Manufactures, etc., at Vienna,” by the author, Was.h.i.+ngton, 1875.
Of these cla.s.ses, the third is of most interest, as exhibiting most perfectly the importance and variety of the work which the steam-engine is made to perform. On the later of these vessels, the anchor is raised by a steam anchor-hoisting apparatus; the heavier spars and sails are handled by the aid of a steam-windla.s.s; the helm is controlled by a steering-engine, and the helmsman, with his little finger, sets in motion a steam-engine, which adjusts the rudder with a power which is unimpeded by wind or sea, and with an exactness that could not be exceeded by the hand-steering gear of a yacht; the guns are loaded by steam, are elevated or depressed, and are given lateral training, by the same power; the turrets in which the guns are incased are turned, and the guns are whirled toward every point of the compa.s.s, in less time than is required to sponge and reload them; and the s.h.i.+p itself is driven through the water by the power of ten thousand horses, at a speed which is only excelled on land by that of the railroad-train.
The British Minotaur was one of the earlier iron-clads. The great length and consequent difficulty of man[oe]uvring, the defect of speed, and the weakness of armor of these vessels have led to the subst.i.tution of far more effective designs in later constructions. The Minotaur is a four-masted screw iron-clad, 400 feet long, of 59 feet beam and 26-1/2 feet draught of water. Her speed at sea is about 12-1/2 knots, and her engines develop, as a maximum, nearly 6,000 indicated horse-power. Her heaviest armor-plates are but 6 inches in thickness. Her extreme length and her unbalanced rudder make it difficult to turn rapidly. With _eighteen men at the steering-wheel_ and sixty others on the tackle, the s.h.i.+p, on one occasion, was 7-1/2 minutes in turning completely around. These long iron-clads were succeeded by the shorter vessels designed by Mr. E. J. Reed, of which the first, the Bellerophon, was of 4,246 tons burden, 300 feet long by 56 feet beam, and 24-1/2 feet draught, of the 14-knot speed, with 4,600 horse-power; and having the ”balanced rudder” used many years earlier in the United States by Robert L. Stevens,[102] it can turn in four minutes with eight men at the wheel. The cost of construction was some $600,000 less than that of the Minotaur. A still later vessel, the Monarch, was constructed on a system quite similar to that known in the United States as the Monitor type, or as a turreted iron-clad.
This vessel is 330 feet long, 57-1/2 feet wide, and 36 feet deep, drawing 24-1/2 feet of water. The total weight of s.h.i.+p and contents is over 8,000 tons, and the engines are of over 8,500 horse-power. The armor is 6 and 7 inches thick on the hull, and 8 inches on the two turrets, over a heavy teak backing. The turrets contain each two 12-inch rifled guns, weighing 25 tons each, and, with a charge of 70 pounds of powder, throwing a shot of 600 pounds weight with a velocity of 1,200 feet per second, and giving it a _vis viva_ equivalent to the raising of over 6,100 tons one foot high, and equal to the work of penetrating an iron plate 13-1/2 inches thick. This immense vessel is driven by a pair of ”single-cylinder” engines having steam-cylinders _ten feet_ in diameter and of 4-1/2 feet stroke of piston, driving a two-bladed Griffith screw of 23-1/2 feet diameter and 26-1/2 feet pitch, 65 revolutions, at the maximum speed of 14.9 knots, or about 17-1/2 miles, an hour. To drive these powerful engines, boilers having an aggregate of about 25,000 square feet (or more than a half-acre) of heating-surface are required, with 900 square feet of grate-surface.
The refrigerating surface in the condensers has an area of 16,500 square feet--over one-third of an acre. The cost of these engines and boilers was 66,500.
[102] Still in use on the Hoboken ferry-boats.
Were all this vast steam-power developed, giving the vessel a speed of 15 knots, the s.h.i.+p, if used as a ”ram,” would strike an enemy at rest with the tremendous ”energy” of 48,000 foot-tons--equal to the shock of the projectiles of eight or nine such guns as are carried by the iron-clad itself, simultaneously discharged upon one spot.
But even this great vessel is less formidable than later vessels. One of the latter, the Inflexible, is a shorter but wider and deeper s.h.i.+p than the Monarch, measuring 320 feet long, 75 feet beam, and 25 draught, displacing over 10,000 tons. The great rifles carried by this vessel weigh 81 tons each, throwing shot weighing a half-ton from behind iron-plating two feet in thickness. The steam-engines are of about the same power as those of the Monarch, and give this enormous hull a speed of 14 knots an hour.