MUSEUM, REGISTER, JOURNAL, AND GAZETTE. No. 790.] SATURDAY, SEPTEMBER 29, 1838. [Price 6d. DR. ROGER'S IMPROVED MODE OF ARRANGING A SAND BATH. ROGERS'S DESCRIPTION OF A CONVENIENT MODE OF ARRANGING A SAND BATH. (From the Franklin Journal.) The practical chemist is always more or less incommoded by the corrosion of the balances and other delicate pieces of apparatus in his laboratory, by the gases and vapours evolved during the processes upon his sand bath. He is moreover subject to uncomfortable heat in the apartment from the necessity of keeping his bath at an elevated temperature. To obviate these inconveniences, I have devised an arrangement, the description of which may be useful to those pursuing the subject. The accompanying figures represent the construction of one which I have now in use. a, figs. 1, 2, represents a nine inch sheet-iron stove, without its ordinary top, while b shows a rectangular sheetiron bath, two feet long by 18 inches wide, made to fit as a top upon the stove; the heated air from the stove is then made to circulate under the sand bath, before it can pass out through the pipe. c, fig. 3, represents the stove and sand bath, in place, surrounded by brick-work. d is a chamber in which the stove is placed, and corresponding in size to that of the sand bath. The fuel is introduced into the stove through the hole e, and the ashes removed through f. The chamber is made to communicate with the external atmosphere, by holes in the outer wall, against which the arrangement is built. The effect of the body of air circulating around the stove is to prevent entirely the wall of the chamber from becoming heated. 9 represents a window in the wall of the building occupied by wire gauze, through which the vapours pass out, while their escape into the apartment is prevented by the moveable sash, seen in front. Thus at the same time that the operator has completely under his eye and control all his process, he is entirely exempt from the inconveniences of the common forms of sand baths. shire, South Wales, in November 1831, I was informed that several explorations had been made in that great range of mountain land denominated "the Cusup Hills," and that the explorers had succeeded in extracting both coal and iron. I understood a bar of metal had been made of extremely good quality; but of the quality and quantity of coal extracted from the same depot I cannot speak. Hope was flattering the minds of the inhabitants, that the little, neglected, and obscure town of Hay would speedily become a mart of the first-rate traffic and wealth; but seven years have since rolled on without producing, as far as I know, any verification of the expectation. I have just perused the last part of the Penny Cyclopædia, (although a work of by no means safe authority to quote) which says, speaking of Hereford, that "no coal or productive ore has been discovered here," so that in the absence of better sources of information, I am constrained to suppose that the above-mentioned enterprise has turned out an unlucky and abortive undertaking. Perseverance and capital are necessary features in all mining transactions, although chance will sometimes put her hand upon a prize, which the most untiring industry will fail to possess itself of. This was the case in that remarkable development of natural wealth, which was exhibited in the copper works at the Parys mountains in Anglesea, North Wales, and which was brought to light by one of the merest accidents which could possibly occur. A countryman (so says village tradition), travelling across a piece of ground which he had traversed hundreds of times before, by chance struck his foot against something which he felt to be a hard substance, which caused him "to measure his length upon the ground;" upon recovering his equilibrium, and looking for the cause of his fall, he perceived upon the surface of what appeared to him to be a large rough stone, some peculiar shining marks or scorings, which were caused by its having come into contact with the iron nails of his shoes. Curiosity prompted him to examine this specimen more minutely and on stooping down with the intention of lifting it from the ground, he found he could hardly move it; but with considerable exertion he got it upon his shoulder. As the village curate's house Your obedient servant, Marlborough-terrace, REPORT ON LONDON FIRES, &c. Sir,-At the recent meeting of the British Association, at Newcastle, Mr. Rawson read a report before the statistical section," On the fires of London," comprising a detailed account of the character, causes, &c., of 3,359 fires which have occurred in and about the metropolis during the five years that the London Fire-engine Establishment has been in operation; viz.: from 1833 to 1837, both inclusive. This report, which is founded upon my annual papers on this subject in your pages, has since appeared in No. 5 of the Journal of the Statistical Society of London. At the conclusion of Mr. Rawson's reading "Reference was made to the great excess of fires in the southern counties of England over the midland counties. This was attributed, by Sir Charles Lemon and Mr. Felkin, to the use of thatched roofs. It was also stated, that Newcastle, notwithstanding the vast consumption of coal in that town, is remarkably free from fires of dangerous magnitude: and it was suggested whether, as the greater number of fires occurred in London about eleven o'clock at night, the practice of raking out the fire at bed time, which is not done at Newcastle where coals are cheap, might not have some connexion with these conflagrations."* Had Mr. Rawson studied the "analysis given of the presumed causes" of fire, I should think he would have had little difficulty in refuting this hypothesis. From the list of causes given in my annual reports, it will be seen, that a very large portion of each year's fires originate from carelessness in the use of candles; the bringing of which too near to bed, and window curtains, &c., cause numberless accidents about bed time. I know that many well-informed persons hold an opinion, that raking out a fire is a dangerous and absurd practice, yet the number of conflagrations that can be traced to this cause is infinitely small. The accidents from unextinguished coal fires, although comparatively few, are much more numerous than the preceding. Mr. Rawson 66 I remain, Sir, London, Sept. 11, 1838. riage. a a are two cylinders fitted with pistons and rods b b, and made perfectly air-tight to constitute pneumatic springs, and fixed at each end of the frame-work of the carriage; cc are the heads of the piston rods, connected with the first of the elliptical springs d d, which is the traction spring, and which is contained in the box e; ff are bars of timber constituting the buffers, and connected to the above system of springs by the rods gg: these rods pass through oblong square holes formed in the end of the carriage frame, and are connected to the piston-rods by compass joints at h h, in order to allow of lateral motion. Thus Fig. 2. it will be seen, that when any concussion takes place the piston is driven by the shock towards the centre of the carriage, thus forming a vacuum in the opposite end of the cylinder, offering a powerful resistance, and constituting a vacuum spring. After the receipt of the shock the piston is forced back to its former place by atmospheric pressure, aided by the metallic springs. Figs. 2 and 3 exhibit the contrivance for connecting and disconnecting two carriages; fig. 2 being a front view of the buffer bar f, and fig. 3 a section taken through, when connected; a is a strong piece of iron inserted in the cen Fig. 3. tre of the buffing barf, and having an eye formed in it to receive the connecting bolt b, which also passes through the other buffing bar c, and forms a swivel joint working in the metal bush d. It will be seen that there is a space or opening left in the buffing barf, to allow of the vertical action of the con necting link a. The connecting bolt 6 has a passage or groove formed upon its head, to allow a small spring to act upon it with just sufficient pressure to keep it in its place. Now, in order to disconnect any one carriage from the train while the whole is in motion, the connecting bolt may be lifted or raised by pulling the cord e, which may be either attached to a pulley or lever, and thus any number of carriages may be disconnected without stopping the whole. RUSSIAN WEIGHTS AND MEASURES. Sir,-As you have been pleased to insert in your vol. 27, the article I sent you from hence concerning Russian weights, as calculated with such great accuracy by my late father, I now send you a summary statement of various measures, and something more concerning weights. I am aware that the subjects are not such as to interest the generality of the readers of your valua ble and scientific publication, and that they may partly be found in other works, but most certainly not in your pages. Your readiness in inserting what I sent you, shows your wish to impart every species of knowledge to every class of your readers, the very many, in consequence of the instructive contents and reasonable purchase of the Mechanics' Magazine, are most certainly under very great obligation to its enlightened conductors, though I am sorry at times to read so much petulancy (to use the softest word) inserted in your pages by gentlemen of science and education; certainly no man can be censured for expressing his sentiments, but it is the manner the opinion is expressed which is objectionable. Excuse this digression. I am, Sir, your obedient servant, BENJAMIN HYNAM. St. Petersburg, July 12, 1838. O. S. |