MARINE ENGINES.

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SPECIFIC NOTICES OF MARINE ENGINES.

The oscillating engines of the Great Eastern are the largest yetmade, there being four paddle cylinders of 74 inches diameter and14 feet stroke; the diameter of the paddle wheels is 58 feet.

The oscillating engines of the Clyde river steamer Columba areprobably the largest yet used in any river steamer, each of thetwo cylinders being 53 inches in diameter, and the stroke 5 ft. 6 in.

The Lord of the Is/es, another large Clyde river steamer, has twodiagonal oscillating cylinders, working on the same crank pin. Thediameter of these cylinders is 46 inches, with a 5 feet 6 inchesstroke. These steamers are fitted with surface condensers.

In the Post Boy, a vessel of 65 tons and 20 horse-power, built onthe Clyde in 1820, the late Mr. David Napier appears to have trieda surface condenser, consisting of a series of small copper tubesthrough which the steam passed, and was Condensed by a circulationof cold water on the outside of the tubes.

The Fairy Queen, the first iron steamer plying on the Clyde,launched in 1831, had an oscillating engine.

The steeple engine, first introduced on the Clyde about 1836 byMr. David Napier, is a convenient form of engine for river boats.It consists essentially in an overhung triangulär frame from thecrosshead, on which hangs the connecting rod. This frame androd are connected with the piston by either one or more pistonrods. In the earlier forms one rod was commonly fixed to thelower part of the triangulär frame, in other forms two and oftenfour piston rods are used.

The side-lever engine was extensively used in paddle-wheelsteamers, the arrangement being very much that of an invertedbeam engine.

The first paddle steamer to cross the Atlantic from Britain wasthe Sirius, built at Leith in 1837, and engined by Messrs. Wingate& Co. of Glasgow . The Great Western, built at Bristol, also madethe passage, the two arriving in New York about the same time.The Sirius measured 178 feet long by 25 feet 8 in. beam, depth18 feet 3 in., and was 450 tons register. She was fitted with twoside-lever engines of 270 horse-power; diameter of cylinder 60 in.,stroke 6 feet; paddle-wheels 24 feet diameter with twenty-twofloats, and appears to have had Hall’s surface condensers.

The Cunard steamer Scotia, the last great ocean-going paddle-