shoulder. As the village curate's house was only a few roods off, he determined to take it to that gentleman for his inspection. This was no other than the late Rev. Mr. Hughes, father to the present Lord Dinorbin, who was then living in extreme poverty upon a paltry stipend of thirty pounds a year. This worthy person's optics being better adapted for metallic discoveries than those of the simple countryman, soon discovered it to be a lump of the purest copper ore. If he was pleased in the first instance at such an unexpected discovery, how much were those pleasurable sensations increased, when he learned from his untutored companion that the spot upon which he had found this treasure formed a portion of his own paternal estate! The immense subterraneous wealth now soon brought to light, has been the source of all the subsequent riches of the Hughes family, and the house of Dinorbin now flourishes among the loftiest peers of the highest house of Parliament. I remain, Sir,

Your obedient servant,
ENORT SMITH.

Marlborough-terrace,

Albany-road.

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 Londons

whether, as the greater number of fires oc curred 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 " observed, that the number of fatal fires had greatly increased," which is not the fact; there is an apparent increase, which I have explained, by stating, that in consequence of the prompt application now usually made for the firemen's assistance in every case of fire, they are frequently called out to accidents arising from the ignition of wearing apparel on the person, which terminate fatally,-these cases, being reported, swell the number of fatal fires, although they do not in reality constitute what is generally understood by this expression. Had all the accidents of this kind last year, been attended by the firemen and reported, they would, being upwards of one hundred in number, have given the appearance of a frightful increase in fatal fires.

I remain, Sir,
Yours respectfully,
WM. BADDeley.

London, Sept. 11, 1838.

ROWLEY'S PATENT BUFFING APPARATUS FOR RAILWAY CARRIAGES.

In our 783rd Number we described the rotary steam-engine patented by Mr. Rowley, of Manchester, and we now,

* Vide Athenæum, No. 566, page 637.

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 dd, 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 b 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.

PA is a stout bench, constructed on the usual principles, except that B is a moveable apparatus, by means of which boards may be fixed on the bench, for planing, &c.; it is also found very convenient for many other purposes. CC is a kind of hollow or trough, which takes up nearly the whole length of the bench; nails, chisels, and other small tools may be placed in it, in order to avoid unnecessary encumbrance on the bench. D is a ratchet stave to support, at any given

height, the hook z, on which boards to be planed edgeways are allowed to rest, whilst one end is engaged in the screw E.. F is a stout cramp-iron, which, being put in one of the holes in the middle of the bench, will, by means of two or three blows with the mallet on the projecting part 2, acquire a firm hold of every object placed under its extremity y.

I remain, Sir, yours respectfully,

Twickenham, Sept. 5, 1838.

P. O.

[We now resume our publication of the American experiments upon steam boiler explosions. The subject has, by recent events, assumed a character of melancholy and paramount importance; we hope, therefore, that our readers will not think that so large a portion of our pages as it will be necessary to devote to them, is done so needlessly. The late act of the American Congress was founded upon these reports, and as it is in contemplation to enact some measure of a similar nature in Great Britain, the experiments detailed will be examined by all interested in steam machinery, with interest. As we have so recently published the Act of Congress itself, we shall only now insert those parts of the proposed bill which were not adopted by the American Legislature, and which referred to proposed arrangements of machinery.]

49. Second.-The undue heating of parts of a boiler may be produced by deposits.— No cause of undue heating is better made out than this one, and the remedy is of the most simple kind.

The water of all rivers contains, in suspension, in greater or less quantities, the muddy particles detached from their banks or beds, and may contain in solution, salts derived from the same sources, or from the springs which supply the stream. The water of springs generally contains so large an impregnation of saline matter, as to decompose soap. The rivers of our Atlantic States, where perfectly fresh, contain few dissolved impurities, while many of those of the Western States are highly charged with calcareous matter. When waters holding substances in suspension, or solution, are evaporated, a sediment is deposited, varying in nature with the water employed. As the quantity of solid matter contained in the water varies, so the time required for such a deposit to take place, from the feeding water of a steam boiler, must be very variable. If a deposit is allowed to remain in a boiler it gradually increases in thickness and in density; the heat which before passed rapidly from the metal to the water, is now impeded by a mass of viscid or of solid matter, which is a bad circulator or conductor of heat, and the temperature of the metal rises. The sediment thus heated increases in denseness, and may even form a hard crust upon the bottom of the boiler. A complete non-conducting coat is thus formed, which, is from

its nature liable to crack or fissure, may allow water to have access to the heated metal below, and produce an explosion. This supposition is, however, as will be seen, by no means necessary to such a result. The most usual action of the sediment would seem to be as follows: When it has accumulated in thickness, sufficiently to produce a temperature in the metal, at which its strength is inadequate to bear the pressure without extending, it yields, and becoming more and more attenuated, finally bursts. It seems that the first yielding may bring water in contact with the metal so as to cool it, when the steam produced is not sufficient materially to increase the pressure within the boiler. Thus the attenuation may increase for a considerable time and gradually, and at last the bursting not produce any more injurious effect than to stop the working of the engine.

Accidental circumstances of figure, heat,&c., seem frequently to determine the places of deposit of these masses of sediment, but it is principally observed at the fire-end of the boiler, where its presence is most dangerous.

50. The committee have derived much information of a practical kind on this subject, and coming as it does from entirely different quarters of the country, where the water depositing the sediment was of different qualities, the details agree very remarkably.

Col. S. H. Long* describes a deposit found in one of the boilers of the Western Engineer, a boat used in the exploring expedition of 1818. The sediment had collected in less than two days so as to be two inches thick, and was found in parts of the boiler, where, from its construction, the heat was greatest. A difficulty in making steam enough for the supply of the engine, was observed, and induced an examination of the boilers, in one of which, the metal at a particular spot was found to have been made to project an inch and a half. In this case timely precaution prevented further evil consequences.

51. The plan of "blowing off" the lower parts of the fluid in a boiler, which is very generally used in turbid streams to the West, is, no doubt, of considerable service while the boat is running, but should never be used as a substitute for cleaning the boilers, when opportunity is afforded for this complete operation. Indeed it must be carefully executed, since, if the flues are bared by it,

* Replies to Circular of Com. on Expl. No. II.