Auxiliary,
Two auxiliary high pressure condensing engines are fixed, adjacent to the paddle engines, for working the pumps and performing other necessary duties on board of the ship; these auxiliary engines are equal to 60 horse-power and can be worked to double that power if necessary.
and Screw engines.
But the screw engines are even more surprising than those of the paddles: they are also of 1000 horse-power with four oscillating cylinders each 84 inches in diameter with 4-feet length of stroke and performing 50 revolutions per minute. They can work up to 4500 horse-power with steam in the boiler at 15 lbs. and revolving at 45 strokes a minute, the expansion valve cutting off at one-third of the stroke; but, with steam at 25 lbs., without expansion, and cutting off at one-fourth of the stroke, they can propel with a power of 6000 horses, so that the combined force of paddle and screw engines gives the tremendous power of 11,000 horses! The propeller shaft, in two parts, is 160 feet in length and weighs 60 tons, while the screw-propeller itself is 24 feet in diameter with 44 feet pitch. The paddle-wheels are, however, still more stupendous, being no less than 58 feet in diameter with a boss which alone weighs 16 tons, each wheel when complete weighing 90 tons.
Abaft the bulkhead of the screw engine-room are placed two auxiliary engines of 20 horse-power each for moving the screw-propeller, when the larger engines are disconnected, at such a velocity as will prevent the speed of the vessel from being retarded when the ship is under weigh with paddles alone, or when under sails and paddles.
There are, also, two auxiliary high pressure engines, each of the nominal power of 10 horses, for working the pumps, shafting, or other parts of the machinery, and for hoisting sails, taking in or discharging cargo, lifting the anchor, and for performing many other services usually carried on by the crew.
Donkey-engines.
Each set of boilers is provided with donkey-engines, with independent boilers, and pumps of power sufficient to feed both sets of boilers, and are capable of being connected or disconnected, so that one donkey-engine may supply any set of boilers. These are each of about 10 horse-power.
Proposed accommodation for passengers, &c.
This mighty vessel was destined to afford accommodation for 4000 passengers, viz., 800 first class 2000 second class, and 1200 third class, independently of the ship’s complement of crew, amounting to about 400. The series of saloons, which were elegantly fitted and furnished, together with the sleeping apartments (as will be seen by referring to the longitudinal section in the [frontispiece] to this volume) are situated in the middle of the ship and extend over 350 feet of her length.