position most approved in practice, is held there by the screw at the lower part of said frame. G G are the treadles which work the cranks. The wheel B, with the crank propellers and adjusting frame, are all fixed in a straightforward direction on the spindle, which works freely in and passes through part of the frame C; consequently, the guiding is effected by a kind of side pressure, similar in effect to that of a person pushing a boat, when his hands are applied to some external object, as an abutment.*

A few advantages expected to be derived from this arrangement, over any I have yet seen, I shall endeavour to point out; and any fallacy which may appear, or any improvement which may suggest itself to any of your ingenious readers, I shall feel pleasure in its being pointed out. I anticipate, when the speed is once attained, (which, on a good hard Macadamised road, will be readily done,) it can be easily kept up by one complete stroke of the treadles to about four revolutions of the large wheels, which, being 24 feet in circumference, makes a clear distance of 32 yards, or about 7 smart strokes for every 200 yards! The operator continually rests on his right foot, which clears the propellers of the ground, and allows the guide-wheel to run freely:† there ought to be a stout spring, or counterpoise by "dead weight," for the purpose of carrying the crank over the upper centre, as connected with the right foot, for as he rests on that foot, it will need a help to start it. The cranks ought to be so adjusted with respect to each other, that just as the propeller is touching the ground, the mans's greatest force is operating on the crank (i. e. when it is at right angles with the treadles ;) then the point of the propeller describes an elliptic, which will strike the ground more or less, according to the position of the sliding frame B, which lifts the wheel and fore-part of the vehicle off the ground, and drags the hinder part after it. Of course, the guide-wheel has already acquired a certain degree of motion, and therefore there is no check when it again reaches the ground.

⚫ I had almost forgot to remark, that there ought to be a circular spring "brake," on which the ope rator might lay his right hand, and stop the carriage instantly, without any strain on the machine.

+ The dotted lines or slide will show how I mean: when the traveller eases up his foot, the weight having power or the propeller the crank begins to act.

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With regard to the two machines described by Mr. Baddeley, I beg leave to state that I saw them tried fifteen years ago, in this town, by some good workmen, of the name of "Kilburn," and either way, (i. e. by using a handle or treadles to the cranks of the large wheels,) they were such hard work that they were speedily laid aside. Another great benefit I anticipate from my arrangement is, that the hind wheels being disconnected, will make the machine turn with more facility, as the inner wheel can stand comparatively still, while the outer one works right round it.

I beg also to recommend the following modification of the above arrangement for steam-carriages on common roads, whereby the engines may be made of much less power, considerably lighter, and more effective. I am aware that Mr. Gurney and others have used propellers, but theirs have been placed, invariably, underneath the whole weight of the carriage and engine, thus constraining it to lift the whole of that weight in the circular part of the stroke. Now, I would propose that the engine, carriage, and load, should be all pretty nearly balanced on two wheels, (moving freely and independent of each other, as in an ordinary carriage;) further, that the preponderance ought to lean on the third, or guide-wheel. The arrangement may be also such, as that the engine shall be always working slowly, only accumulating power at one part, and throwing it out briskly at that part of the stroke where it is most effective. The two propellers might, perhaps, be more efficiently placed by using two guideframes, one a little in advance of the other, so that when one propeller had lifted the fore-part of the carriage, and dragged it forward, the other one-its guide being more in advance-would give the whole a smart push, and so keep up or increase the velocity required.

In all the machines of this kind I have yet seen described, the traveller had harder to work, the quicker his pace; in this machine it is the reverse. I remain, Sir, Yours respectfully,

Bishop Auckland.

WM. PEARSON.

REMEDY FOR SPONTANEOUS COMBUSTION

OF COALS-ARMAMENT OF H. M. STEAM
FRIGATE "GEYSER."

Captain Carpenter, of Her Majesty's steam frigate Geyser, has suggested the following remedy for spontaneous combustion.

It is proposed to have several cast-iron tubes, with holes at the lower part, as shown in the following figure, passing into the bunker or coal-hole, nearly to the bottom

of the vessel, and only a few inches from the ship's side, properly secured. The upper parts of these tubes are to come up to the deck, and to be contrived so as to give ventilation without allowing wet to go down amongst the coals. At the same time, means are to be afforded of pouring water into the bunkers, so as to flood them at the bottom in case of ignition. The water, in that case, would have a twofold effect, as it would not only extinguish the fire at the place where danger is to be apprehended, but at the same time the water poured into the tubes would destroy all ventilation, and would have a tendency to smother the part ignited.

The cause of spontaneous combustion is, evidently, first, the accumulation of gases from the moisture of the coals; and then, either heat or friction gives rise to ignition. To obviate this evil, if you allow the atmospheric air to pass freely amongst the coals, of course the gases could not accumulate, and combustion would not take place. If, however, there should be parts where the air did not penetrate, then the remedy is effected by pouring water into the bottom of the coalbox, and extinguishing the fire. The smoke issuing from the tube on deck would always give timely notice of danger; and the hose on deck, pointed

into the upper part of the tube, would provide a sufficient supply of water always at hand. The tubes would be about six inches in diameter, and about a quarter of an inch thick; their length would be regulated by the depth of the coal-box.

Hay-stacks are provided with the same remedy against taking fire, by introducing a large basket tube down the centre; and why should not the same result take place in the manner proposed?

The Geyser is to be fitted, under Captain Carpenter's able direction, with several things which are likely to give rise to improvements in naval warfare. In the first place, she is to have two guns weighing 114 cwt. each, to carry solid shot and shell. The range of these guns will be five thousand yards, and they will carry further than any gun that has yet been cast, by 400 yards. This vessel will, consequently, have it in her power to disable the largest ship in the world, and at the same time to keep out of harm's way.

The pinnace of the Geyser will be fitted with a small disc engine, and Captain Carpenter's patent propellers. This boat will be used occasionally as a tug, to assist ships in calms; or, should the machinery of the Geyser be injured by shot in action, this boat could tow her out of danger. The boat could also be used with advantage in towing boats filled with troops, especially such boats as those fitted over the paddle-boxes on Captain Smith's plan, (with which the Geyser is also provided,)-in watering a fleet-in sounding a-head of a fleet, in navigations like those of China-in communicating with ships at a great distance, where it would be impossible to pull with cars, &c. &c.

BURSTING OF EMPTY PIPES.

N.

Sir, Mr. Claxton's off-hand explanation of the above "singular phenomenon" lets in no new light upon the matter; he has gone upon the groundless supposition that one part of the syphon was outside the house, the other inside. This is incorrect-the whole is external, and not liable to any such vicissitudes as are imagined.

To Mr. C., and the other correspondents who attribute the bursting of the

For a full description of these see Mech. Mag., vol. xxxiv. page 258.

pipe to the condensation of vapour, the formation of water, and subsequently of ice, I beg to say, that if such an effect could possibly have been traced to such a cause, "my stock of general knowledge" would, I apprehend, have been quite adequate to the solution of the problem.

The difficulty arises solely from a positive knowledge that no water whatever was either formed or collected within the ruptured pipe, and to some far more subtle agent or agents must the mischief be attributed.

What these may be I have yet to learn, and remain

Yours respectfully,

London, Feb. 21, 1842.

WM. BADDELEY.

SELF-INKING PRINTING press.

Sir, I am at present making a model of a new description of typographic press, the chief novelty of which consists in its not requiring the aid of a workman to supply the necessary ink, which is accomplished by means of a simple and effective apparatus fixed to the end of the "table," or that part of the press on which the form of types is laid. The "platen" of the new construction has grooves, or other suitable means of fastening stereotype plates thereto, and a solid block of wood of the height of ordinary type is placed on the table of the press; this done, the inking rollers are adjusted, so that when the table is drawn out by means of the winch, the plates attached to the platen receive the amount of ink required. The usual "tympan" is not employed, as in other presses; its place is occupied by the "frisket," cut out, of course, according to the nature of the work. When it is desired to produce impressions by the press, you place a layer of smooth cloth, or flannel, on the block of wood resting on the table, and stretch and nail it fast at the edges. You then place the sheet of paper on this, and turn the frisket down; next roll the table under the platen and draw it down, with the requisite pressure; then draw out the table again, when, on lifting the frisket, the work will be found complete; while, at the same time, the plates are partly inked for the following impression. The rollers, consequently, go twice over the plates before they are printed from.

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I would have sent you a drawing of the whole, but I consider the description here sufficiently explicit to enable any mechanic to construct a press on this plan, or to alter to it any of the Stanhope, Albion, or other hand-presses in use. The kind termed the "Ruthven," is, I consider particularly adapted for the purpose, although the one I am now constructing, is of the " Stanhopean" construction, and I feel confident of its answering.

I am at the same time planning a method of adapting the principle to the same presses with ordinary types, without being restricted to the use of stereotype plates, a drawing of which I hope to send you shortly.

Sir, I am, respectfully yours,
M. I. BRAZendale.

February 11, 1842.

DAVIES'S ELLIPTOGRAPH.

Sir,-Will you allow me to point out what appears to me an error in the construction of "Davies's Elliptograph," described in your No. 963 ?

The ellipsis is proposed to be struck from one leg of the instrument keeping in contact with a circular piece of steel, so inclined as to represent the shape required, when you look at it, in a line produced from the stem a, a. Now, if a point were attached to the guide i, that point would trace an ellipsis, whose longest diameter would equal the diameter of the steel disc employed; and the guide will, in all cases, describe such an

ellipse, but the ink-pen described at d, will

move in a line parallel to the small ellipse. Now, ellipses, whose diameters are in equal ratios, are not parallel. For instance: Suppose g be 1 inch ŝths in diameter when inclined 45°, it will cause i to describe an oval, whose diameter is 18ths and 1 inch (roughly); but slide d, so that it shall trace an oval, whose transverse diameter is 24 inches, its conjugate diameter would be about 24th, instead of which, it should be about 18ths. What I mean, in short, is, that the " Elliptograph" would describe ovals by drawing large ones with lines parallel to a small one, which should not be.

An instrument to do what Mr. Davies's professes to accomplish, would undoubtedly be extremely useful, and I am not without hopes that the ingenious inventor will be able to overcome the defect I have pointed out. Sir, I remain your obedient servant, H. P. Lambeth, February 8, 1842.

SIBERIAN GOLD MINES.

Whilst the gold mines of Brazil and Spanish America appear to be yearly falling off in their yield, those of Siberia, on the contrary, are yearly producing more. Nature (says a Russian report) has showered gold in abundance on the soil of Siberia. The eastern part of that vast country is remarkable at this time for its riches in the precious metals. The sands of the rivers there show the presence of gold in their beds from the surface-in many places, for tens of square versts-as for example in the river Grand Birussa, on the borders of the governments of Yenisseisk and Irkoutsk, and in the basins of the Tongouska superior, of the Oudérei and the Pile, which water the first of those governments. From the savage country it used to be, Siberia has become the realm of gold; its riches may now be accounted such, although the road to them has been paved with silver, it may be said, and made good by persevering industry.

The explorations of the gold mines have been chiefly extended by private adventurers from the example of those worked by the Crown. Excepting the districts belonging to the imperial mines of Kolyvano Voskressensk and Nertschinsk, or the country situated beyond the Baikal, the adventures of gold mining, and the search for veins of gold, in all the rest of Siberia, have been surrendered to private enterprise on certain conditions. For a long time the speculators searched fruitlessly in the deserts of that vast country, and lost their capitals and their health; but at length nature yielded to the perseverance of man, gold was discovered, and its working commenced in 1829. From this date it is curious to observe the rapid development of private (alone) gold mining in Siberia, according to the following official statement:

rather more than 36lbs. British avoirdupois weight.

Thus in ten years the production has increased from 1 to 212 poods per annum, from private enterprise alone. But, in fact, the year of gold mining consists of the four months of summer only, during which the washings of the gold sands, and the extraction of gold takes place in Siberia, and particularly in its eastern parts; and it is proper to notice that all the workings were conducted by people of no experience in that branch of industry, in a country altogether unknown, covered with thick forests, impenetrable morass and mountains, where no trace of the passage of man could be found, and where savage hunters had scarcely ever set foot.

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The year 1841, will, however, it is said, furnish a more irrefragable proof still of the immense mineral wealth of Siberia. Private enterprise will have extracted from it nearly 100 poods of gold more than in 1840. In this amount will be included for nearly 35 poods from the deposits discovered last year by the trader Miasnikoff, the working of which has not employed more than 300 labourers. "What other industry," says the report, can, with ten men only, produce in the space of four months only, to the amount of 50,000 silver roubles of a substance which is of never-varying demand and value?-The silver rouble, it may be noted, is equal to about 3s. 24d. sterling. -At present the adventurers confine their enterprises to the gold to be found among the sands of the rivers, and so long as they are successful they are likely to carry their researches no farther; but the question arises, and the solution will some time or other be sought, whence do these golden sands derive their supplies? When the river workings, which may suffice for the present age, fail, it is probable that more extensive researches will trace the mineralogical treasures of Siberia to their source.-Mining Journal.

ABSTRACTS OF SPECIFICATIONS OF ENGLISH PATENTS RECENTLY ENROLLED.

ANTHONY BERNHARD VON RATHEN, OF KINGSTON-UPON-HULL, CIVIL ENGINEER, for a new method or methods (called by the inventor, "The United Stationary and Locomotive System) of propelling locomotive carriages on railroads and common roads, and vessels on rivers and canals, by the application of a power produced or obtained by means of machinery and apparatus unconnected with the carriages and vessels to be propelled.-Enrolment Office, Jan. 28, 1841.

This system of propulsion is proposed to