them; and the ship 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 manœuvring, the defect of speed, and the weakness of armor of these vessels have led to the substitution of far more effective designs in later constructions. The Minotaur is a fourmasted screw iron-clad, 400 feet long, of 59 feet beam and 261 feet draught of water. Her speed at sea is about 121 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 ship, on one occasion, was 7 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 feet draught, of the 14knot speed, with 4,600 horse-power; and having the "balanced rudder" used many years earlier in the United States by Robert L. Stevens,' 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 feet wide, and 36 feet deep, drawing 24 feet of water. The total weight of ship 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,

1 Still in use on the IIoboken ferry-boats.

1

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 134 inches thick. This immense vessel is driven by a pair of "single-cylinder" engines having steam-cylinders ten feet in diameter and of 4 feet stroke of piston, driving a two-bladed Griffith screw of 23 feet diameter and 26 feet pitch, 65 revolutions, at the maximum speed of 14.9 knots, or about 17 miles, an hour. To drive these powerful engines, boilers having an aggregate of about 25,000 square feet (or more than a halfacre) 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.

Were all this vast steam-power developed, giving the vessel a speed of 15 knots, the ship, 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 ironclad itself, simultaneously discharged upon one spot.

But even this great vessel is less formidable than later vessels. One of the latter, U. S. S. Indiana, is a longer, wider and deeper ship than the Monarch, measuring 420 feet long, 75 feet beam, and 25 draught, displacing over 11,500 tons. The great rifles carried by this vessel weigh 60 tons each, throwing shot weighing a half-ton from behind iron plating 14 feet in thickness. The steam-engines are of about twice the power of those of the Monarch, and give this enormous hull a speed of 16 knots an hour.

navy

The of the United States does not to-day possess a fleet of power even approximating that of either of several classes of several other foreign powers.

The largest vessel of any class yet constructed is the Great Eastern (Fig. 146), begun in 1854 and completed in

1859, by J. Scott Russell, on the Thames, England. This ship is 680 feet long, 83 feet wide, 58 feet deep, 28 feet draught, and of 24,000 tons measurement. There are four paddle and four screw engines, the former having steam-cylinders 74 inches in diameter, with 14 feet stroke, the latter 84 inches in

diameter and 4 feet stroke. They are collectively of 10,000 actual horse-power. The paddle-wheels are 56 feet in diameter, the screw 24 feet. The steam-boilers supplying the paddle-engines have 44,000 square feet (more than an acre) of heating-surface. The boilers supplying the screw-enAt 30 feet draught, this great vessel The engines were designed to de velop 10,000 horse-power, driving the ship at the rate of 16 statute miles an hour.

gines are still larger. displaces 27,000 tons.

The figures quoted in the descriptions of these great steamships do not enable the non-professional reader to form a conception of the wonderful power which is concentrated within so small a space as is occupied by their steam-machinery. The "horse-power" of the engines is that deter

mined by James Watt as the maximum obtainable for eight hours a day from the strongest London draught-horses. The ordinary average draught-horse would hardly be able to exert two-thirds as much during the eight hours' steady work of a working-day. The working-day of the steamengine, on the other hand, is twenty-four hours in length.

The work of the 30,000 horse-power engines of the Lucania could be barely equaled by the efforts of 40,000 horses; but to continue their work uninterruptedly, day

in and day out, for weeks together, as when done by steam, would require at least three relays-120,000 horses. Such a stud would weigh 60,000 tons, and if harnessed "tandem" would extend ninety miles. It is only by such a comparison that the mind can begin to comprehend the utter impossibility of accomplishing by means of animal

The

power the work now done for the world by steam. cost of the greater power is but about one-tenth that of horse-power, and by its means tasks are accomplished with ease which are absolutely impossible of accomplishment by animal power.

It is estimated that the total steam-power of the world is about 90,000,000 horse-power, and that, were horses actually employed to do the work which these engines would be capable of doing were they kept constantly in operation, the number required would exceed 150,000,000.

Thus, from the small beginnings of the Comte d'Auxiron and the Marquis de Jouffroy in France, of Symmington in Great Britain, and of Henry, Rumsey, and Fitch, and of Fulton and Stevens, in the United States, steam-navigation has grown into a great and inestimable aid and blessing to mankind.

We to-day cross the ocean with less risk, and transport ourselves and our goods at as little cost in either time or money as, at the beginning of the century, our parents experienced in traveling one-tenth the distance.

It is largely in consequence of this ingenious application of a power that reminds one of the fabled genii of Eastern romance, that the mechanic and the laborer of to-day enjoy comforts and luxuries that were denied to wealth, and to royalty itself, a century ago.

The magnitude of our modern steamships excites the wonder and admiration of even the people of our own time; and there is certainly no creation of art that can be grander in appearance than a transatlantic steamer a hundred and fifty yards in length, and weighing, with her stores, five or six thousand tons, as she starts on her voyage, moved by engines equal in power to the united strength of thousands of horses; none can more fully awaken a feeling of awe than an immense structure like the great modern iron-clads (Fig. 145), vessels having a total weight of 10,000 to 15,000 tons, and propelled by steam-engines of as many horse