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to remember that commerce was the source of the modern prosperity of Italy. But commerce cannot exist. without freedom-a truth that princes and people have yet to learn here.
“The palaces of all the ancient Roman nobility have, in the entrance hall, a crimson canopy of state, beneath which the prince sits on a raised throne to receive his. vassals, hear their complaints, redress their grievances, and administer justice. Perhaps I ought to speak in the past, rather than the present tense ; but they still exercise a sort of feudal jurisdiction over their numerous tenantry-among whom their will is law.
“Above the door of every palace, upon the escutcheon of the family arms, we seldom fail to see the S. P.Q. R. all that is left of the senate and people of Rome.”
In the summer of 1823, the Bachelor and his Nymph projected a tour to Scotland; but in what vehicle was a question that occasioned some discussion between them. Benedict was strongly in favour of a steamer, and urged many reasons, as to speed, novelty, and economy, why they ought to prefer that mode of conveyance. The Nymph, however, pled not only her feminine timidity against all the agencies of fire and water, but contended that the state of the ma
chinery in those sort of vessels was still in so rude a · condition, that no person of a true philosophical mind
would risk himself in them. “ They may do very well,” said she, “ for people of practical feelings, and habituated experience, but to those who have a correct theoretical conception of the accidents to which the machinery is liable,—the brittleness of the iron, the explosive powers of the steam, the negligence of the engineers, the unknown gaseous substances in the fuel,—the risk of unsoundness in the timber work,—the uncertainty of the winds, the hazards of the waves, and all the manifold ordinary perils of navigation, besides those that peculiarly attach to machinery, and particularly to that of the steamengine, it would argue almost a brute disregard of consequences, to prefer a steamer to a smack ; and who would not prefer a carriage to all the aquatic vessels that have been built since the time of Noah's ark ?"
“ You are indulging yourself in fears little more creditable than hypochondriacal terrors,” replied the Bachelor. “I am assured, on the most perfect report, that the steamers are as safe and safer than any other mode of conveyance whatever.”
6 The thing is quite impossible,” said Egeria.
The invention is but still in its infancy. Give me the thirteenth volume of the Edinburgh Review from the shelf behind, and I will convince you by its history."
“ The first idea of the steam-engine is found in the writings of that celebrated projector, the Marquis of Worcester, who, in the year 1663, published a small tract, entitled, “ A Century of Inventions,".consisting of short heads, or notices of schemes, many of them obvi.
ously impracticable, which at various times had suge gested themselves to his very fertile and warm imagi. nation. No contemporary record exists to illustrate or verify his description of the contrivance which we presume to call a steam-engine, or to inform us where, and in what manner, it was carried into effect; though it is evident, from his account, that he had actually constructed and worked a machine that raised water by steam. His description of the method is short and obscure; but inclines us to think, contrary to what many have supposed, that the force of his engine was derived solely from the elasticity of steam ; and that the condensation of steam by cold was no part of his contrivance. This last, we believe, was the invention of Captain Savary, who, in 1696, published an account of his machine, in a small tract entitled the Miner's Friend, haying erected several engines previous to that period. In these engines the alternate condensation and pressure of the steam took place in the same vessel into which the water was first raised, from a lower reservoir, by the pressure of the atmosphere, and then expelled into a higher one by the elastic force of strong steam.
“ Steam, it must be observed, was thus employed merely to produce a vacuum, and to supply the strength that was applied, for a like effect, to the sucker or piston of an ordinary pump; and it was a great step to have discovered a method of bringing the air to act in this manner, by the application of heat to water, without the assistance of mechanical force.
“ The next essential improvement was made by Newcomen, for which he obtained a patent in 1705. It consisted in separating the parts of the engine in which the steam was to act from those in which the water was to be raised; the weight of the atmosphere being em. ployed only for the purpose of pressure, and the steam for that of first displacing the air, and then forming a vacuum by condensation. Newcomen was thus enabled to dispense with the use of steam of great and dangerous elasticity, to work with moderate heats, and to remove at least some part of the causes of wasteful and ineffectual condensation. To him we are indebted for the introduction of the steam cylinder and piston, and for their connexion with the pump by means of the main lever with its rods and chains; to which we might add several other subordinate contrivances, which do great credit to his ingenuity.
“ Still, however, the machine required the constant attendance of a man to open and shut the cocks at the proper intervals, for the alternate admission of steam and cold water: and although traditional report attributes the invention of the mechanism by which the engine was made to perform this work itself, to the ingenuity of an idle boy, we know that the contrivance was first perfected by Mr Henry Beighton 1717, who also improved the construction of several other parts of the engine. From this time to the year 1764, there seems to have been no material improvement in the structure of the engine, which still continued to be known by the appellation of Newcomen's, or the atmospheric engine. The boilers, however, had been removed from under the cylinder in some of the larger engines, and the cylinder had been fixed down to a solid basis. Still the steam was condensed in the cylinder; the hot water was expelled by the steam; the piston was pressed down by the weight of the atmosphere, and kept tight by being covered with water. It was moreover considered as necessary that the injection cistern should be placed on high, in order that the water might enter with great force. It had been found by experience, that the engine could not be loaded, with advantage, with more than seven pounds on each square inch of the piston ; and the inferiority of that power to the known pressure
of the atmosphere, was, without due consideration, imputed wholly to friction. The bulk of water, when converted into steam, was very erroneously computed; the quantity of fuel necessary to evaporate a given quantity of water was not even guessed at ; whether the heat of steam is accurately measured by its temperature was unknown; and no good experiment had been made to determine the quantity of injection water necessary for a cylinder of given dimensions. In a word, no man of science in this country had considered the subject since Desaguliers ; and his writings, in many respects, tended more to mislead than instruct.
“ Such was the state of matters, when, fortunately for science and for the arts, Mr Watt, then a mathematical instrument-maker at Glasgow, undertook the repair of the model of a steam engine belonging to the University. In the course of his trials with it, he found the quantity of fuel and injection water it required, much greater in proportion than they were said to be in large engines; and it soon occurred to him, that this must be owing to the cylinder of this small model exposing a greater surface, in proportion to its contents, than larger cylinders did. This he endeavoured to remedy, by making his cylinders and pistons of substances which conducted heat slowly. He employed wood prepared on purpose, and resorted to other expedients, without producing the desired effect in any remarkable degree. He found also, that all attempts to produce a greater degree of exhaustion, or a more perfect vacuum, occasioned a disproportionate expenditure of steam. In reflecting upon the causes of these phenomena, the recent discovery, that water boiled in an exhausted receiver at low degrees of heat (certainly not exceeding 100 degrees of Fahrenheit, but probably, when the vacuum was perfect, much lower), occurred to him; and he immediately concluded, that, to obtain any considerable degree of exhaustion,