A very compact and convenient fire engine has lately been invented by Mr. Baddeley, consisting of only one cylinder placed horizontally, and working on the principle of De la Hire's double-acting pump. The ordinary up and down motion of the handles, by means of a simple contrivance, causes the piston to traverse backward and forward within the cylinder, each side being alternately filled with water which the returning stroke expels. There are two entrance valves lying at the bottom of the cylinder, one at each end, and two exit valves, situated immediately over the former. The water enters at the bottom of the cylinder, and is discharged at the top, the stream being equalized by a globular air vesseL The inventor considers the advantages of this engine to consist in its compact form, great strength, and durability ; that it has fewer working parts, is lighter, and has less friction than any other engine of equal power.
Of all the engines hitherto constructed and worked by manual labour, the floating fire engine is the most powerful. Engines of this kind generally consist of three cylinders, working into an air vessel of large dimensions, and are built in appropriate barges. They are put in motion by the power of from forty to fifty men, applied to four long revolving cranks, which, by suitable machinery, work the three pistons. These engines will throw a column of water, one inch in diameter, upwards of a hundred feet high. They are advantageously employed on the river and in docks, where an abundant supply of water can always be depended upon.
These engines, however, have been greatly surpassed by the fire engines recently constructed by Mr. John Braithwaite, worked by steam power. The last of this kind, the Comet, built for the Prussian goverment in 1832, had two working cylinders ten inches and a half in diameter, with a fourteen-inch stroke, the steam cylinders being twelve inches in diameter. When working with a steam pressure of seventy pounds upon the square inch, and making eighteen strokes per minute, this engine threw a jet of water, an inch and a quarter in diameter, nearly one hundred and twenty feet high. The same
power gave two jets of seven-eighths of an inch, and afterwards four of five eighths- of an inch, an elevation of about eighty feet. The consumption of coke was three bushels per hour, and the average working of the engine was calculated to be equal to the discharge of between eighty and ninety tons of water per hour.
Numerous attempts have been made to condense a powerful fire engine into a small compass. In this respect Capt. Fisher, R.N. appears to have been most successful ; his engine, on Newsham's principle, consisting of two five inch cylinders, with eight-inch strokes, and an air vessel situated between them, was comprised within a box the size of an ordinary tea chest, exclusive of the handles, which fixed on the outside, and served to carry the engine by. The purposes for which this kind of engine is suitable are so few, that they have not been very extensively used ; for the local purposes only of mansions, manu factories, or on ship board, can they be advantageously employed.
Much ingenuity has been exercised to construct a fire engine on the rotatory principle, but without success. An ingenious one of this kind was the invention of Mr. Rangeley, for which he took out a patent. It consisted of two fluted rollers, working into each other, while their opposite sides worked in semi cylinders, with which they were in close contact, the ends of the rollers being similarly circumstanced ; each space between the flutings came up filled with water, which was discharged by the flutings exactly fitting into each other on the descending side. In this, however, as in all the other rotatory steam and fire engines, it was found to be practically impossible to construct an engine sufficiently water tight to stand the great pressure to which they are subject, without incurring an excessive and destructive amount of friction.