and mathematician, in 1624, describes an engine acting by the elasticity of Steam. It consists of a spherical vessel, m, w, placed over a fire. This vessel has two apertures; into one is fitted a pipe, n, which has a stop-cock, o, and funnel a: this supplies water to the boiler. The other orifice has a pipe, x, which descends through the water, until it nearly touches the bottom of the vessel, and rises to some convenient height above it. When the water, c, becomes heated, De Caus says, that the increased bulk of the vapour forces the water up the pipe x, which issues in a jet at b. De Caus was also acquainted with the fact, that Steam could be condensed into its own weight of water; but he appears to have been ignorant of any mode of applying this property to aid the effect of his fountain. The first person in modern times who applied the expansive power of Steam on any scale to a useful practical purpose, was Giovanni Branca, an eminent Italian mathematician, who resided at Rome in the beginning of the seventeenth century. His contrivance was an clipile, from which steam issued, upon a wheel formed with float-boards or vanes like a water-wheel or wind-mill, and thus produced a rotatory movement. This wheel, by some intermediate mechanism, gave motion to the stampers of a mill for pounding drugs. Our Fifth Figure is copied from that given by Branca to explain his invention; but it must be considered only as an ornamental and picturesque illustration of the principle by which he produced the moving power in his stamping-mill; not as a view of any part of the machinery which was actually constructed. a, is a boiler in the shape of a Negro's head. b, a pipe proceeding from it, which conducts the steam upon the vanes or boards of a wheel, x. Other wheels, e, f, are attached in the usual manner to communicate the motion in the required direction.* It is on account of this contrivance that Branca is considered by his countrymen to be the inventor of the Steam Engine; and even in a recent English work on the subject, he is allowed the merit of a first idea. To this he certainly has no claim; neither can his engine be compared with Hero's for its ingenuity, nor to De Caus's for its efficiency. Besides, long before this period, the same mechanism was described by Cardan as moved by the "vapour from fire." And the mere substitution of steam by the Italian philosopher is not so original or important, as to give to the transition the rank of an invention. Branca was, however, a man of much ingenuity, and many of his machines are highly creditable to his abilities as a scientific mechanic. The elasticity of the vapour of water, which had long been known to philosophers, but to them only, had now become familiar to water-work artists; and in their hands it was applied in a variety of ways to their favourite problem of raising water above its * Branca's account of his contrivance is contained in a folio volume of machines, which he dedicated in 1628 to a M. Canci, Governor of Loretto. It was published at Rome in 1629, under the title of "Le Machine diverse del Signior Giovanni Branca." Our engraving is contained in plate XXV of that collection. + Partington's Historical Account of the Steam Engine. London, 1822. level in jets and fountains. Without vouching for the great effects said to be produced by these machines, we will describe two, as necessary to give a clear notion of the value of these conceits, and as specimens of the ingenious absurdities, which, under the name of Air Engines, were recommended even by experienced engineers about this period. The machines themselves, under another form, are to be found in the Spiritalia. The book from which they are extracted in their present shape was one of some reputation in its day, and many years after its publication it was thought worthy of being translated into English. The translation went through two editions.* 66 The Sixth Figure represents a Very subtil engine to raise Water by means of the Sun;" which, according to its inventor, "hath great effect in hot places, as in Spain and Italy; because in those places the sun shines almost always with great heat, especially in the summer." And they are to be constructed after this manner : about a foot You must have four vessels of copper, (in our engraving we have only shewn two, n, n,) well soldered round about, each of which must be square, and eight or nine inches high. A pipe, s s, is placed on each vessel, having other pipes, w, w, attached to it, reaching almost to its bottom. A "New and useful Inventions for Water Works: a work both useful and delightful for all sorts of people; translated into English by John Leak." The plates appear to have been those used in the French edition. |