In one of the old tracts preserved in the library of the London Institution there is a very curious representation of a steam-boat, constructed by an engineer of the name of Hulls. And this individual, now so little known, was undoubtedly the first who applied a steam-engine to the purpose of navigation.
To impel a vessel by this means, two paddle wheels, like those used in an under-shot water-wheel, are connected by means of a long axis and crank, with the working beam of the steam-engine; and if this motion is not found sufficiently rapid, a wheel and pinion are added, which, although it decreases the effective power of the engine, yet increases the velocity of the paddle wheels.
To illustrate the great advantages possessed by the steam-engine, even in its rudest state, over every other species of prime mover yet enumerated, it may now be advisable to examine its effective force when employed in the working of pumps. It has been found that one hundred weight of coals burned in an engine on the old construction, would raise at least twenty thousand cubic feet of water twenty-four feet high; an engine with a twenty-four inch cylinder doing the work of seventy four horses. An engine on Capt. Savery's plan, constructed by Mr. Keir, has been found to raise nearly three millions of pounds of water, and Mr. Watt's engine, upwards of thirty millions of pounds the same height.
To the mining interests this valuable present of science to the arts has been peculiarly acceptable; as a large portion of our now most productive mineral districts must long ere this have been abandoned, had not the steam-engine been employed as an active auxiliary in those stupendous works. In the draining of fens and marsh lands, this machine is in the highest degree valuable; and in England, particularly, it might be rendered still more generally useful. In practice it has been ascertained that an engine of six-horse power will drain more than eight thousand acres, raising the water six feet in height; whilst the cost of an engine for this species of work, including the pumps, will not exceed seven hundred pounds. This is more than ten windmills could perform, at an annual expenditure of several hundred pounds; while, in the former case, the outgoings will not exceed one hundred and fifty pounds per annum. To the mariner also, the steam-engine offers advantages of a no less important and novel nature than those which have already been described. By its use he is enabled to traverse the waters both against wind and tide, with nearly as much certainty, and, as the machinery is now constructed, with much less danger, than by the most eligible road conveyance. It too frequently, however, happens that the faults of any new invention are unjustly magnified, while its real advantages are seldom duly appreciated; and this axiom has been fully verified, in the clamour so unjustly raised against the application of the steam-engine to nautical purposes. Accidents are now, however, but of rare occurrence; and it is more than probable, that the great improvements which have been made in the boiler and safety-valve will effectually secure these parts of the engine from a recurrence of such tremendous explosions as characterised the first introduction of steam navigation. And, lastly, the political economist must hail with the most heartfelt gratification, the introduction of so able and efficient a substitute for animal labour as the steam-engine. For it has been calculated that there are at least ten thousand of these machines at the present time at work in Great Britain, performing a labour more than equal to that of two hundred thousand horses, which, if fed in the ordinary way, would require above one million acres of land for subsistence; and this is capable of supplying the necessaries of life to more than fifteen hundred thousand human beings.[11]
An ingenious foreigner, who lately visited England, has published an estimate of the mechanical force set in action by the steam-engines of this country.
He supposes that the great pyramid of Egypt required for its erection the labour of more than 10,000 men for 20 years:—but if it were required again to raise the stones from the quarries, and place them at their present height, the action of the steam-engines of England, which are managed at most by 36,000 men, would be sufficient to produce the same effect in 18 hours.
THE END.
LONDON:
PRINTED BY C. ROWORTH, BELL YARD,
TEMPLE BAR.