THE STEAM ENGINE.
Reading edition
[Lectures on the Steam-Engine, by the Rev. Dionysius Lardner, LL. D. 4th Edit. 12mo. London, 1832. Taylor. Price 7s. 6d.]
This is decidedly the best popular account which we have of the Steam-Engine,—the most accurate and complete and at the same time the most intelligible and interesting. The book is intended for the use of unscientific readers, or of the public generally; but it has the unusual advantage, for a work of this description, of being written by a person of the highest scientific acquirements. The utmost dependence, therefore, may be placed on the correctness of the various descriptions and explanations it presents; they are stripped indeed of those technicalities which would have rendered them both repulsive and obscure to ordinary readers,—but the substance of the statement which remains, although thus transformed from a full and precise detail to a general outline, is still, in so far as it goes, perfectly clear and satisfactory. The volume contains all that most persons, with the exception of engineers and mathematicians, can be supposed desirous of knowing about the exceedingly curious and important subject of which it treats. It both describes the steam-engine as it now exists, and it relates its origin and past history. After a preliminary lecture on the natural forces on which the action of the contrivance depends, the author proceeds to recount and describe the successive inventions and improvements of the Marquis of Worcester—of Captain Savery—of Newcomen and Cawdley—of Humphrey Potter (the boy who first hit upon the plan of making the engine work its own valves),—and finally of the illustrious Watt. The various parts of Watt’s single and double-acting engines are explained with the fulness which their importance deserves in the fifth and the three following lectures, the modifications which since his time have been introduced in the valves, the boiler, the furnace, &c., being also noticed. The ninth lecture is occupied with an account of the double-cylinder engines of Hornblower and Woolf, and also of a very ingenious and elegant machine, possessing certain peculiar and valuable recommendations, suggested by the late Reverend Mr. Cartwright, the well-known inventor of the power-loom. These expositions are in general distinguished by very remarkable clearness—and, illustrated as they are by abundance of excellent woodcuts and copper-plates, they can hardly fail to be perfectly and easily understood even by those who have been but little accustomed to such investigations.
The part of the book, however, on account of which we principally notice it at present, is the new matter which appears for the first time in this edition, and which relates to the two latest among the various extraordinary applications of the power of steam;—the wonders that have been performed by it on the Liverpool and Manchester railway, and the still more recent experimental achievements of the several projectors who have for some time past been endeavouring to introduce steam-coaches upon our common roads. The two long chapters which are devoted to these subjects, the first especially, contain a number of facts which had not previously been laid before the public, and some of which are of considerable interest.
The locomotive (or travelling) engines which are employed on the Liverpool railway are all what are called high-pressure engines. One of Watt’s most ingenious contrivances was his condensing apparatus, by which, previous to every stroke of the piston, he created a vacuum in the part of the cylinder through which it had to be driven, and thereby enabled it to be sent forward through that space with a much inferior pressure of steam to what would otherwise have been required. But in the steam-engines affixed to coaches it is found convenient to dispense with this apparatus, on account of its complexity, its weight, the room which it would occupy, and above all the constant supply of cold water which would be requisite to keep it in action. The consequence is that in these engines and others similarly constructed, a much greater force of steam is necessary to make the piston do its work; and they are on that account denominated high-pressure engines. It is only within the last thirty years that they have been introduced, and the most remarkable proofs of their power have been afforded on the Liverpool railway, which was opened only about two years ago.
Some time before it was opened a contest took place on this railway between three different steam-coaches. The Rocket, constructed by Mr. Stevenson; the Sans-pareil, by Mr. Hackworth; and the Novelty, by Messrs. Braithwait and Ericson, for a prize of £500, offered by the Directors to that which should accomplish the greatest distance in the shortest time. On this occasion the Rocket, which gained the prize, went over the space of 30 miles in 2 hours 6 minutes and 49 seconds, being at the average rate of 14⅕ miles per hour. But in the course of the journey it sometimes proceeded at the rate of above 29 miles an hour, and its slowest motion was about 11½ miles in that time[1]. In May last, Dr. Lardner saw the engine called the Victory draw on the same rail-road the weight of 92 tons 19 cwt. 1 quarter, in twenty waggons, together with its tender containing fuel and water, from Liverpool to Manchester, a distance of 30 miles, in 1 hour 34 minutes and 45 seconds, besides 10 minutes spent in taking in water. The speed on this occasion was in some places 25½ miles an hour, and on level ground, where there was no wind, it was generally 20 miles an hour. On another day, the engine called the Samson drew fifty waggons laden with merchandise, and, with itself, making a gross weight of above 233 tons, the same distance in 2 hours and 40 minutes, exclusive 263of delays upon the road for watering, &c., the rate of motion having varied from 9 to 16 miles an hour, and being on an average nearly 12 miles an hour. The coke consumed in this journey was 1762 lbs., or a quarter of a pound per ton per mile. The attendance required is only an engine-man and a fire-boy, the former of whom is paid 1s. 6d. for each trip, and the later 1s. The expense of the original construction of the engines, however, and of their wear and tear is very great, though not nearly so great on the latter account, Dr. Lardner assures us, as has been sometimes stated. The price of one of the most improved engines at first is about £800, and it will travel from 25,000 to 30,000 miles without costing as much more for repairs. Notwithstanding many extra expenses which this undertaking, as the first of the kind, has had to bear, and from the experience purchased by which future speculators will profit, it has been perfectly successful in a commercial point of view. The profits on the capital invested have been from the first above 6 per cent. per annum; and during the latter six months of 1831, it was at the rate of above 8 per cent. per annum; and it has since probably exceeded that amount. The original £100 shares already sell for above £200. On the other hand the advantages to the public have been as great as to the proprietors. Fully 600,000 passengers now pass by the rail-road in the course of the year between Liverpool and Manchester, or four times as many as used formerly to make the journey. The transference of merchandise is also effected both with infinitely greater speed, and at a vast reduction of expense.
Some time ago a work was published by Mr. Gordon, the engineer, on the application of steam as a moving power for coaches on common turnpike roads, the facts contained in which were principally derived from the report on this subject of the Committee of the House of Commons, which was ordered to be printed on the 12th of October last. Dr. Lardner has here availed himself of the information supplied by the same most interesting and important parliamentary paper; some of the curious details given in which we may possibly take another opportunity of laying before our readers. In the meanwhile we can only afford room for the general conclusions to which the Committee came on the evidence brought before them. They are as follows:—
“1. That carriages can be propelled by steam on common roads at an average rate of ten miles per hour.
“2. That at this rate they have conveyed upwards of fourteen passengers.
“3. That their weight, including engine, fuel, water, and attendants, may be under three tons.
“4. That they can ascend and descend hills of considerable inclination with facility and safety.
“5. That they are perfectly safe for passengers.
“6. That they are not (or need not be, if properly constructed) nuisances to the public.
“7. That they will become a speedier and cheaper mode of conveyance than carriages drawn by horses.
“8. That, as they admit of greater breadth of tire than other carriages, and as the roads are not acted on so injuriously as by the feet of horses in common draught, such carriages will cause less wear of roads than coaches drawn by horses.
“9. That rates of toll have been imposed on steam-carriages, which would prohibit their being used on several lines of road, were such charges permitted to remain unaltered.”
The toll-bills complained of have since been repealed. “At the moment that I write,” says Dr. Lardner, “several steam-carriages are in process of construction for regular work upon the public roads of England. Some are about to be established between Paddington and the Bank, upon the New Road; others between London and Greenwich, and other places in the vicinity of the metropolis. Another it is stated, is to run between London and Birmingham. The first impulse once received, the progress will be rapid, and the effect of proportionate importance.”