must be imbedded, as it were, in coal

tar,

and the bolts well covered with it, previously to their insertion. Both the bolts and nuts should be made hot, so as to dissipate all humidity from off their surface, at the time of dipping them into the tar. I suppose that the bolts will be about seven-eighths, and the nuts about three inches square.

A thread tapped in the slate in the way I speak of, in No. 642, would stand any other kind of force than that to which it will be subjected in the railholding case, perfectly well; but the hardest substances which, like all kind of stones, are brittle and friable, are not calculated to resist the sort of shocks and jars from the passing trains, in such parts as the threads of a screw. With metal nuts, the bolt need not be screwed further than a couple of inches, whereas, according to the other plan, much more would be required.

While on this subject, I should like some of your readers to see the hardening and strengthening effects of coal-tar applied to tiles and bricks for coping. They would be much pleased with the result. A composition of coal-tar and sifted road-scrapings forms a substance for coping walls, or other analogous purposes, more impermeable and imperishable than any stone. A little dry lime added to it, is an improvement. As I have explained in the Mechanics' Magazine ten years ago, linseed, or even whale oil, applied to the soft and perishable Portland stone, and even to the soft Bath sandstone, when quite dry, gives it the hardness and durability of marble. Coaltar has the same effect; the only objection to it is the colour. But that may be remedied by subsequent whitewash ing. Even marble exposed to the air in this country, ought to be protected in the way I have been advising these ten years past.

A union takes place between gelatinous and oleaginous fluids, and various earths and stones, which can only be compared to the process of fosilization in the very hard agatized parts which we find imbedded in stones comparatively soft; such as the oysters and amonites in limestone, the fossil fish in coal and other deposits, and the flints in chalk, all evidently caused by a combination of the animal juices with the earths surrounding them. Thus I look upon

chalk formations, with their regular layers of flints, to have been successive deposits of lime in mechanical suspension in water upon a body of moluscæ, laying on the thin surface, or which sank down to it from out the fluid mass of chalk (lime), the latter itself, probably, the detritus of shells. Water is actually solidified in its union with lime, so are the substances I have been speaking of, and with other earths and oxides besides. After many years' attentive observation of nature, I have come to suspect, that the modii of matter we call metals, originate in what we term "organic action. For example, in the Mechanics' Magazine, in Nov. 1828, it will be seen that I attribute the main part in the production of iron to the vegetative operations of forests, the green colour of the leaves being caused by the presence of iron, as is also the brown assumed by the same leaf at a later period.

I have the honour to be, Sir,

Your obedient humble servant,
F. MACERONI.

Dec. 6, 1835.

THE GREENWICH RAILWAY,

Sir,-Now that the Greenwich Railway has become rather a popular topic of conversation, I am beginning to get heartily sick of the exclamations which one hears constantly repeated in their ears, of" What a clever, what an original idea, that of carrying the rail over continuous arches, and converting those otherwise useless bins' into profitable shops, warehouses, private dwellings, &c.!!!" No one has a legitimate right to complain of any engineer for adopting a good idea, whenever suggested; but I cannot, I confess, either respect or admire the candour or ingenuousness of that projector who silently takes credit for what really does not belong to him. Does Colonel Landmanu, in fact, claim the exclusive authorship, except by adaptation, of this plan? Can he deny having seen, heard, or read of his model elsewhere? And will he now at once frankly and honestly acknowledge where he found it? Because, sir, if he do not, and promptly, I shall inform him.

In the meanwhile, Mr. Editor, it may amuse your readers to guess." To my knowledge, the idea of carrying a public

thoroughfare or promenade over arches, &c., did not originate in America, Asia, Africa, or the British dominions; neither in France nor Belgium, Holland or Switzerland; no State in Germany or Italy; neither Spain or Portugal can claim the honour. Finally, Sweden, Denmark, and Norway, Russia, Prussia, Austria, Poland, Turkey, together with all the islands, foreign and domestic, are alike innocent of the "prodigious" thought now about to generate steam from London to Greenwich. The question, then, is, "Do you give it up, sir ?" Till then, or the solution of my riddle by some of your numerous, and ingenious, and really ingenuous correspondents,

I beg to remain,
Your obedient servant,

P. S. H.

RECENT AMERICAN PATENTS. (Selected from the Franklin Journal for October, 1835.)

CASTING CHILLED ROLLERS, AND OTHER METALLIC CYLINDERS AND CONES, James Harley, Pittsburg, Pennsylvania.-" In order to show the object of my improvement," says the patentee, "I state the usual method as now practised in casting chilled rollers, as follows. The mould in which they are cast consists of a main central portion, formed by a hollow metallic cylinder, and the two ends, called journals and couplings, which are moulded in sand.

"Now, if the metal be poured into such a mould in the usual manner, that is, through a tube descending to its lower extremity, the motion thus communicated to it, as it rises in the mould, tends to throw all the sand, dross, slag, &c. towards the external part of the roller, and thereby occasions cracks, flaws, and other imperfections on its surface; therefore, in order to obviate this injurious tendency, it is the custom to stir the fluid metal with a rod, so as to give it a rotary motion, in order, by this stirring, to bring But this the light substances to the centre. operation of stirring is dangerous, and does not effect its object with certainty.

"My method of construction is, to insert a pipe or pipes (which may be called gates) at openings into or near the bottom of the main chill eylinder, or near the inner surface of the said cylinder; and the line of direction of said pipes or gates is not to be that of a perpendicular to said bottom or inner surface, but that of an oblique or slanting line, usually equal to about thirty degrees, that is, approaching the direction of a tangent to the cylinder. Beneath these open

ings, by which the pipes enter the main chill cylinders, is to be formed a circular chamber, with as many openings as there are pipes to communicate with the openings into the cylinder, and the pipes are to connect this chamber with the cylinder in the oblique or slanting direction above described; it is also advantageous to have this circular chamber closed by a partition across it, on one side of the opening in the circumference, left for the insertion of the descending tube, by which the fluid metal is to be poured in.

"This is the construction of my improvement; the manner of using it is as follows. The melted metal is poured in at the descending tube, by which it arrives at the opening at the bottom of this tube leading into the circular chamber; here the metal enters, and on one side being arrested by the partition closing the chamber at the side of this opening, the stream or course of the metal will be driven to the other, and, consequently, continued round. The partition is to be so placed as to give the course of the stream in the same direction round as that to which the pipes or gates lean.

"The metal flowing up these inclined tubes or pipes, acquires a rotary motion on entering the main cylinder, which is the object I wish to attain, thereby preventing the necessity of stirring with a rod; and this rotary motion is necessary, in order to bring the light substances to the centre, and throw the heaviest and best metal to the circumference."

A COOK STOVE, Joel Rathbone, New York. -After stating that inconveniences have been experienced from the construction of the ordinary Jew's-harp, or flat cook stove, from the waste of heat, the burning out of the front oven plate, and the unequal distribution of heat through the oven, the patentee describes the improvements by which he proposes to obviate these inconveniences; they are, "first, in recessing, by a curve line or sweep, so much of the front furnace plate as lies below the kettles, in such manner as to bring the face thereof more or less under the bottom of the kettles; and, secondly, in opening on the back side between the furnace and the oven, and between the flue that passes over and the flue that passes under the oven, a horizontal passage for the air to circulate through."

A FISHING BOAT, John Donn, Washington. The advantage proposed to be obtained by the improvement in the fishing boat here patented, is, (principally, an increased length of leverage for the oarsman. This is accomplished by extending wings on each side of the boat, from stem to stern, these wings being carried out horizontally by means of knees, thus widening the upper

part of the boat, whilst that portion of it which is in the water remains as usual. The oarlocks are, of course, placed on the outer edges of these wings, which have the ordinary finish of gunwales. Some incidental advantages from this arrangement are mentioned, such as securing the boat from the effects of the swell, and thereby lessening the risk of foundering; the increase of room, also, for the seine, which, as usually placed altogether in the stern, raises the bow out of the water. The claim is to the wing constructed as above described, and applied to a fishing boat.

TAILORS' SHEARS, John Andrews, New York. The upper side of the lower bow or ring of the shears, is to be made flat, or widened out, so that the fingers which press upon it in the act of cutting, may exert their power without the inconvenience experienced in the uses of shears as ordinarily made. The claim is simply to the widening out this part, as described.

WATER CLOSET, James Stone, New York. -This improvement consists of a pendu lous weight attached to a rod, and connected by joints to the pan of the water closet. The specification refers throughout to a drawing, which exhibits the plan very perfectly. The contrivance is very simple, and appears to be extremely well adapted to its purpose, without a liability to get out of order.

AN IMPROVEMENT IN THE MODE OF CATCHING FISH, Charles Fowler, and Edwin R. Hanks, Connecticut.-A steam-engine is to be erected on the shore for the purpose of paying out the seine, and drawing the boats to the shore. Two blocks are to be fixed out in the stream at such distance apart as shall be equal to the length of the seine, and at the centre point between these blocks, two others; corresponding blocks are to be placed on the beach, so that two endless bands, or ropes, may be drawn around them, forming, when in use, two quadrangles. The ropes on shore are to be drawn by the steam-engine. Two batteaux, each containing one-half the seine, are to be drawn from the shore to the centre blocks, where they are to be cast off, and again made fast outside of the blocks; by drawing upon the ropes, the seine is then made to pay out each way to the outer blocks.

"What we claim as our invention, is the drawing the said boats from the shore around their proper circuits for paying out the seine, and then to the shore, by means of steam power, in the room of rowing; and likewise said drawing in of said seine by said engine."

We think the foregoing form of claim ex

ceptionable, as it merely refers to the use of steam for drawing a rope, or ropes, which certainly is not the invention of the patentees; the proper subject of the patent, we appre hend, is the arrangement of the ropes to enable them to effect the purpose intended, whether steam or animal power be employed.

AN IMPROVEMENT IN THE USE OF THE SAW, Anson Field, Jericho, Vermont. - By the improved use of the saw, the patentee means an improved mode of fixing the saw for use, the purpose to which he proposes to apply it being, principally, the cutting of wood for the fire, in doing which he proposes to cut through a log at a single stroke, provided the saw be long enough.

Cheeks of wood, or iron, are to be fixed on each side of a saw, embracing it between them in such a manner, that at one end the teeth shall rise but little above them, whilst at the other the blade is to project sufficiently to pass through a log. This is then to be placed between slides, so as to allow it to slide back and forth like the frame of a millsaw, as may be most convenient," and "where thought best," "the timber to be cut confined to it as may be most convenient;" the saw to be moved "by means of any machinery thought best to attach it to." "By this process, a stick of timber of any size may be taken off by one sweep of the saw, provided it be of sufficient length, and width at the back end. The saw may be graduated so as to cut from half an inch to two inches to the foot, according to the size and nature of the timber to be cut." "What I claim is the manner of confining it between the two slips; the way in which it slides, and the principle on which it cuts, viz. being so confined as to cut, at one sweep, the entire width of the saw above the slips."

We have thus placed before the reader the whole sum and substance of the invention, and it will be perceived that those persons who wish to carry it into operation, are left at ample liberty to devise the means of doing so. It is probable that a twenty-horse power steam-engine may suffice to work the saw, and cut through a nine-inch log at a single sweep, a powerful screw-press, or some analogous instrument, being employed to hold the log.

PLOUGH, William Hess, Pennsylvania.— "The improvement for which the patent is asked consists in, 1st. The flanch on the mouldboard behind the share, to prevent that part of the plough cutting in the furrow, and thus running heavy. 2d. The running the landplate back to the plough-handle, and attaching it to the handle, and extending the cutter back to the handle, by which the plough is strengthened, and the earth will not fall over the landplate into the furrow.

3d. In extending the land side of the share back to the plough-handle, and attaching it to the landplate near such handle, by which the plough runs lighter, and there is less trouble in working from the whole of the land side to the share being in one piece." There are no references to the drawing.

PREPARATION OF CHEWING TOBACCO, Edward Chassaing, Baltimore.-The tobacco manufactured by the patent process is denominated "Natural Roanoke Leaf," and it is thus prepared: 250lbs. of the best Virginia tobacco is to be sprigged in the usual manner, and sprinkled with a mixture made by boiling 3lbs. liquorice, 2 lbs. prunes, 1 lb. figs, 1lb. table salt, gall. Jamaica rum, and 4 galls. water. The liquid is to be strained, and water enough added to make the liquid amount to four gallons. The tobacco is then to be lightly pressed, as discolouration would be produced by heavy pressure.

The claim is to "the manufacture of chewing tobacco in the manner hereinbefore described."

NOTES AND NOTICES

In Rebuilding that part of the Penitentiary tha was burnt. I would suggest that the gutters should be lined with zinc instead of lead, which would be much more economical, and in case of another fire, might prevent its spreading in the manner so disastrously exemplified at the late fire; as I have heard that the lead guttering was melted, which left the ends of the rafters exposed to the flames, and was thereby the cause of their spreading to such an extent, which would not have been the case if zinc had been used, as it would have resisted the flames.-HENRICUS.

Steam Plough.-At a meeting of the Grantham Agricultural Association, Mr. Hanley stated that he had seen a steam plough at work in Lancashire, which did its work remarkably well, and turned up an acre of wet land, at a depth of nine inches, in 1 hour aud 50 minutes.

Barton's New Safety Boiler.-(From a Corre spondent.) Mr. J. Barton, the well-known ingenious engineer, has, we are informed, just completed a new invention which promises to be of great utility,: as an improvement in the construction of steam-, engines; and also of importance as a means of diminishing the hazard to which the personal safety of individuals is now exposed, wherever: steam-engines are used. This invention consists in a safety boiler upon an entirely novel principle, and which is so contrived as to afford every protection against injury from explosion. Independently of this primary recommendation, we understand that it combines the further advantages of cheap ness in the original cost and economy in the consumption of fuel. Mr. Barton has not published a description of the plan upon which his model is formed, the patent-right not being yet secured." We must therefore postpone a further account of it until another opportunity, and can only add, that we are assured the invention is likely to prove a grand desideratum in the scientific world, and to give a new impulse to locomotive machinery; especially in conjunction with the inventor's other improvements in the steam-engine; viz, his patent metallic pistons and lubricators, which have long

been extensively adopted, particularly in his Majesty's service.

Railway Phenomenon.-On Monday last a gentleman of this town, who had taken his place in the, hindmost carriage of one of the railway trains from Bolton to Kenyon, witnessed the following singular occurrence-He was placed with his back to the engine, and had a clear view of the receding line of railway. The train was going down the inclined plane from Bag-lane to Leigh, at the apparent rate of from 30 to 40 miles per hour. A man who was standing on the side of the railway threw a stone about the size of a hen's egg in a horizontal direction, and with considerable violence, at the train. The stone was distinctly seen by the gentleman in its progress to the carriage in which he was seated, and, having attained its maximum of velocity, it appeared, like Mahomet's coffin, to be suspended in the air for a few seconds within a foot of the gentleman's head. He seized hold of it, and he describes the sensation which he felt in doing so as somewhat similar to that which would be felt in grasping a stone, in a state of rest, suspended by a thread.-Bolton Chronicle.-[This is easily accounted for; both the train and the stone had attained the same velocity.]-Manchester Advertiser.

Sugar from Indian Corn.-M. Pallas lately presented to the Academie des Sciences of Paris a sample of this substance, extracted from the stem of the plant, which has been found to contain nearly 6 per cent. of sirop boiled to 40 degrees, a part of which will not crystallize before fructification; but it condenses and acquires more consistency from that period to the state of complete maturity. The inost favourable time to obtain the greatest quantity of sugar, is immediately after the maturity and gathering of the fruit. The matter left after the extraction of the sugar, is capital to feed cattle or to make packing paper.

An Air Violin.-A. newly and ingeniously invented instrument has lately been presented to the Academie des. Sciences of Paris, by M. Isoard. It resembles the common vio in, with the strings extended between two wooden or metal blades; it is vibrated upon at one end by a current of air, while at the other the player presses on them, shortening them by the pression of the finger. In fact, the strings of this instrument are acted upon by a current of air, instead of the common bow. The sounds vary between those of the French horn and the bassoon.

. Philo-Scrutator having made his choice (for which we by no means blame him), has no fair claim upon our pages. Besides, all the arguments he makes use of against the Pneumatic Railway scheme are already quite familiar to our readers.

Communications received from Mr. Lush-Mr. Brett-O. G. P.-Mr. Ambrose-Non-Ego-Medicus-Mr. Henderson-Mr. Chapman.

The Supplement to the last volume, containing title, index, &c. and portrait of Charles Vignoles, Esq., C. E., is just published, price 6d. Also, the volume complete, in boards, price 9s. 6d..

Patents taken out with economy and despatch; Specifications prepared or revised; Caveats entered; and generally every Branch of Patent Business promptly transacted. Drawings of Machinery also executed by skilful assistants, on the shortest notice.

LONDON: Published by J. CUNNINGHAM, at the Mechanics' Magazine Office, No. 6, Peterbo rough-court, between 135 and 136, Fleet-street. Agent for the American Edition, Mr. O. RICH, 12, Red Lion-square. Sold by G. G. BENNIS, 55, Rue Neuve, Saint Augustin, Paris. CUNNINGHAM and SALMON, Printers, Fleet-street.