generated fully adequate for working a steam engine, or for other purposes. Fig. 5 is a longitudinal section, and Fig. 6 is a transverse section of this kind of salamander, inclosed in its recipient vessel of a cylindrical form, (though any other convenient figure will answer nearly as well). The mass of cast-iron is for the sake of convenience divided into four pieces, gggg. The two passages ff, leading from the vessel, are to convey the steam to the working cylinder; the stream of water is supplied by the feed pipe a a, and is regulated by the piston z moving in the small horizontal or other cylinder d, which is pressed down by an adjusted spring; the end of the piston rod being connected by means of a joint to a lever, opens the cock b, and admits a plentiful supply of water, but when the supply of water is too considerable, and in consequence too much steam is generated, the piston will be forced up, and the cock gradually shut off, while the superabundant steam will escape by the aperture e. The feed of water is to be supplied by the forcing pump i, to the chamber of which is attached the cylinder 1, with its piston pressed down by a strong spring; by this means the water will be forced in, in nearly an uniform stream; but if the pump gives too great a supply, the superfluous water will be discharged at the aperture m. Figs. 7 and 8 are a longitudinal and transverse sections of a salamander, similar to the one last described, but inclosed in a double vessel or casing; the supply of water, regulated as before-mentioned, will be forced into the space n n, between the two casings, where it will be evaporated into steam, but not so rapidly as when injected immediately upon the heated iron or other substance. The recipient vessels or casings employed for this description of salamander, must be strengthened in propor tion to the pressure they are intended to bear; but this may be done at a very moderate expence, because a vessel required to hold a salamander for working an engine, need not be more than one-third the diameter and length of a common boiler, requisite for the same engine; and apparatus constructed as herein-before described, will completely insure that much desired object, perfect safety with economy. In witness whereof, &c. OBSERVATIONS BY THE PATENTEE. The apparatus described in this patent are offered to the public, as possessing the advantages of being economical, compact, and perfectly safe. To prove their superiority over the common boilers or other apparatus usually employed for raising or containing the vapours of high expansive force, it will be sufficient to advert to the well-known causes of those destructive accidents, the bursting of boilers: this arises from neglecting to make the strength of the boiler in proportion to its capacity; for it is ascertained that the liability or tendency to explosion, in similar shaped vessels containing fluids acting with an expansive force, is in the ratio of their diameters; thus a cylindrical boiler or vessel four feet diameter, will have four times more tendency to explode than a boiler one foot diameter, and the strength or thickness of metal in the former should be four times greater than in the latter. It is also perfectly obvious that the strength of boilers must be in proportion to the expansive force of the steam they are intended to raise; now supposing that steam of 50lbs. to the square inch may be raised with perfect safety in a cylindrical boiler four feet diameter, the metal of which is 1 inch in thickness; if it were required to raise steam of ten times that expansive force (with equal safety), it is clear that the boiler must be made ten times stronger, that is, the metal should be fifteen inches thick; but if it were possible to reduce the diameter of the boiler, say to six inches, the thickness of the metal could then be safely reduced to one-tenth or to 1 inch. Upon these principles, therefore, it is that the salamander is constructed, for the bore or orifice of the strong tube being inconsiderable, it may be strengthened without inconvenience to an almost indefinite extent, as will be readily understood by those who are acquainted with the force acting in the cylinder of an hydraulic press. The salamander may be fitted up so compactly, with its furnace composed of cast-iron plates, as shewn in the drawing, as not to require more than one-third the space of the ordinary boiler, and can be erected at a considerably less expense. The salamander, composed of heaters inclosed in a vessel, is peculiarly adapted for the purpose of working locomotive engines and steam carriages: as it is known that every attempt which has been hitherto made upon machines of this description, has not met with the expected success, this general failure is attributed in great measure to the incumbrance of the common boiler, with the furnace and fuel, and the annoyance of the fire and smoke; the whole of these inconveniencies will in a manner be removed, by employing this description of salamander. Furnaces are proposed to be established at regular stages upon the road, where the heaters may be changed in less time than what is usually occupied in changing horses to a mail coach. Specification Specification of the Patent granted to THOMAS TODD, of Swansea, in the County of Glamorgan, Organ-builder ; for certain Improvements in rolling of Iron, and making Wire, Nails, Brads, and Screws. Dated May 7, 1819. With a Plate. To all to whom these presents shall come, &c. Now KNOW YE, that in fulfilment of the said proviso, I the said Thomas Todd have executed this instrument, by which I do declare that my several improvements in the rolling of iron, and making of wire, nails, brads, and screws, are described and ascertained in manner following; that is to say: First; the improvement in rolling of iron consists in the means of forming or rolling bars or rods of iron, of very regular and equable form and size throughout their whole length, at the same time leaving the corners or angles of such bars sharp and free from flaws or burrs. This is effected by passing the metal between a pair of rollers, each mounted on an axis, in a strong iron frame, in the manner of ordinary rolling or laminating mills for metal. The form and construction of the rollers being the principal object of this part of my improvement, I will describe them with reference to the drawing annexed to this instrument. Fig. 1 (Plate II.) in the drawing, shews a front elevation of the rollers, with their appendages mounted in a strong frame; and Fig. 2 an edge view. The same letters of reference refer to the same parts in both figures. AA, is a strong frame, of cast iron, or other fit material, of an oblong form, having studs or projections B B, CC, formed out of it, to contain and support the brasses a a, cc, for the roller spindles to turn in. One pair of the brasses are stationary, and the other adjustable by screws bb, |