ence of a circle, while the other moves by simultaneous gradations of alternately increasing and diminishing extent. But this is not all that distinguishes the crank.... 2d, It is one of the highest recommenda

tion begun and once more made to cease. At the commencement of the motion downward, a valve is to be opened for the entrance of the steam above the piston, which valve must be closed at the end of the stroke, and at the same instant in which one steam-valve closes, an opposite one must be opened to admit steam below the piston; at the same instant, also, a valve of eduction for the first portion of the steam must be opened, and a second valve of emission on the opposite side of the piston closed. At one and the same instant, therefore, the motion of the piston has to be stopped in one direction and commenced in the opposite direction, one steam communication closed, a second opened, a third of eduction cut off, and a fourth renewed, and all this (for the perfection of the engine) must be done with the most absolute precision.

But these processes, which produce the change of state from rest to motion, and from motion to rest, require time. Matter acquires momentum which must be gradually removed, otherwise that matter is subjected to concussion, as if by the stroke of a hammer, and either suffers or produces injury. And, on the other hand, when in motion, matter requires a force to stop it equal to the force that gives it that motion. These effects, therefore, cannot be instantaneous;* and it is necessary that while the motion which the steam gives off be uniform and continuous, the parts of the engine itself shall be allowed time to be brought to a state of rest, without shock, concussion, or jolt, and as gradually and gently be again urged to their greatest velocity in the oppo- opposite direction. All these with exquisite adjustment the crank effects; it stops the piston as gently and softly as if it placed beneath it a cushion of eider down, and afterwards as gradually begins and accelerates its motion to its highest velocity in the opposite direction. The valves, too, are opened with the same perfect adjustment, being performed with that gradual motion which proportions the largeness of the aperture to the supply of fluid required to be transmitted. An adjustment so complete, could only take place by such a relation as subsists between the crank and piston, the one describing uniformly the circumfer

On sait que pression ne peut pas produire tout-à-coup une vitesse finie."-Lagrange, Mech. Analyt., p. ii. sec. x.

very slight error in its construction shall not very materially prevent its usefulness, nor any slight derangement of its adjustment be attended with immediate destruction, but that on the other hand, the efficiency of the mechanism shall be consistent with such degrees of correctness as ordinary workmen can accomplish, and with such care as ordinary attendants can be trusted to bestow; also, that the progress of disrepair shall be so gradual as to give timely warning of the necessary readjustment. Just such a piece of mechanism is the crank. It is at the top and bottom of the stroke, or in the line of the centres, as it is technically called, that the opening and shutting of the valves should take place; and it is just at this point that pressure on the piston can produce any effect on the crank; but suppose the valves not to open with obsolute precision, suppose them to open and shut too soon or too late, then will the error at that part of the circuit be of comparatively small importance, because, just then, the motion of the piston is so slight, that, through an arc of twenty degrees, it does not describe one hundredth part of a stroke, and the effect of any error in that space will not effect the crank by more than one hundredth part of its amount; any error of adjustment is therefore diminished in effect to one hundredth part of what would be produced, were the motion of the piston to be uniform in portions corresponding to the arc of description, as would be the case in any other species of rotatory conversion.

3d, In like manner, errors arising out of construction, management, or wear, are-diminished one hundred-fold by transmission through the crank. It has been to me matter of frequent astonishment, that although I have seen at the mouths of coal-pits, small mines, and quarries, mere remnants of engines, frail rusty old fragments of iron and wood, working so loose as scarcely to remain upright upon their basements, they were still working within 30 per cent of their full power.

4th, To all these circumstances, I may add, that the constitution of the crank is one reason why an engine may be constructed of enormous weight, and of the most un wieldy dimensions, without being thereby much injured in its working; because the crank acquires so slow a motion at the commencement and termination of the stroke, that it equally slowly communicates motion to all parts of the machine, and in a like manner receives from them the impetus which they give out in the act of being again slowly brought to rest towards the end of the stroke. The impetus, therefore, given to the reciprocating parts of the machine is lent not lost.

We have thus endeavoured to expose the nature of the fallacy under which they labour, who imagine that the present steamengine, as derived from Watt, is a machine which "destroys" or "absorbs" a larger portion of the power it is designed to transmit, and who looked to the rotatory engines as a means of increasing the amount of the power given out in useful effect. That the rotatory engines, which appear day after day, are not new, we show from the fact, that the five great classes which comprehend them all have been invented and re-invented by upwards of ninety individuals. That their inventions have been unsuccessful is manifest from the non-existance of their machines in the daily use of ordinary manufactures. That the failures of these contrivances did not arise from defects accidental to the peculiar arrangements and contrivances of the engines, is rendered probable by the great variety of forms in which they have been re-invented, tried, and abandoned. That they have not failed from deficiencies in the workmanship and practical details, is rendered still more probable by the circums'ance of finding among the names of inventors, those of the most eminent practical engineers We have next shown that in theory, the crank of the steam-engine in common use, cannot as has been supposed, be attended with a loss of power, as such loss would oppose the established doctrines of virtual velocities; it is shown also from very simple and elementary considerations, that what appears to be lost in force, is resumed in velocity-that, in proportion as the mean force on the piston is greater than the mean force on the crank, in that proportion is the space described by the latter greater than the space described by the former. That the dynamical effect produced in a given time Is exactly in the proportion of the steam expended in that given time; and thus have we arrived at the conclusion, that the common reciprocating crank steam-engine has not the faults attributed to it in theory, and which the rotatory engines have been designed to remedy. We have next taken the practical view of the subject-in simplicity of parts the rotatory piston has no advantage over the reciprocating piston; in difficulty of construction the rotatory piston far exceeds the reciprocating engine -it is more expensive at the outset-it has more friction-it is more bulky, and less compact-it is inferior in precision and uuiformity to the crank engine-and there

is a radical fault inherent in the very nature of rotatory mechanism, from which it follows that the rotatory engine can never be rendered either an economical or a durable machine. We have further shown that, even if rotatory engine could be made economical and durable, its very nature renders it unsuited to the great purpose of steam navigation and inland locomotion, -objects to which it has been considered peculiarly applicable. We deemed it an appropriate and instructive conclusion to our inquiry, to examine into the action of the crank, for the purpose of discovering what those remarkable qualities are which have given to the crank of the common steam-engine, its unrivalled superiority as an element for the production of circular motion, and a degree of perfection unattainable by any other mechanism. We heve seen that well-constructed crank steam-engines are daily performing duty, which is within ten per cent. of the therotical maximum of possible effectof obsolute perfection that this practical perfection arises from the simplicity of the crank, from its wonderful adaption to the nature and laws of matter and of circular motion in connection with rectilineal motionfrom its reduction of errors either in construction, adjustment, or management, so as to work well without the obsolute necessity of greater intelligence, expertness, and precision, than belongs to ordinary workmen; and from the compensating nature of the arrangements of its structure, by which it is accommodated, in a remarkable degree, to the necessary imperfections of all human mechanism.

It is my earnest desire, that this exposure may have the effect of inducing some of my ingenious countrymen to direct their exertions for the advancement of the arts and industry of Scotland, to other and more promising subjects of invention. A wide field is open to their exertions in the useful applications of the mechanical powers of the common steam-engine to the wants of growing civilization, and to the improvement of the condition of the human race. them direct their exertions to these objects, with the industry and unity of purpose which they have already displayed in the pursuit of the facinating fallacy of a rotatory steam-engine, and they will one day be reckoned in the glorious list of those who have been the benefactors of their kind, and the ornaments of Scotland.

RECENT AMERICAN PATENTS.

Let

(Selected from the Franklin Journal for March. MANUFACTURING SADDLE-TREES William Kelley, Pennsylvania.-" My improved mode of manufacturing saddle-trees consists

in the substitution of raw-hide for the wood, usually employed for that purpose; to effect which, I proceed in the following manner: After the hair has been removed from the hide, in the usual way, and the hide is properly broken, I draw, or strain it, whilst wet, either over a wooden saddle-tree, or over a mould properly shaped and prepared for that purpose, where it is to remain until it is perfectly dry and hard. Having in this way brought two or more such pieces of hide into the proper form, I unite them together at their edges, by means of rivets, or otherwise; preferring, however, the employment of rivets to any other mode. The pieces of hide are, of course, cut to the proper size and shape for the intended purpose. I sometimes form the tree, or foundation of the saddle, of a single piece of raw-hide, in which case I turn the edges of the hide over, all round the outer and inner edges of the tree, and rivet through the double thickness. To this foundation, or tree, the irons usually employed may be fastened, as to trees of wood. Strips of spring steel, also, may be rivetted on, whenever it may be deemed requisite, so as to increase the stability and elasticity of the whole: I usually affix such a spring all round the under side. After my tree, thus made, has received its proper form, and is ready for covering, I give to it a thick coating of any good water-proof varnish, such as shellac, copal, or gumelastic. In finishing the saddle, any of the known modes of procedure may be adopted, according to the fancy or judgment of the workman."

RAIL-ROAD CARS, Anthony Plantou, Philadelphia. This contrivance exhibits a railroad car upon castors. The running wheels are to be grooved to embrace both sides of the rail, and these wheels are embraced between, and have their gudgeons in two cheeks of metal, which unite at top, forming part of a vertical swivel upon which the wheel, with its embracing cheeks, may revolve horizontally. The claim is, to "the substitution for the axle now in use, of four upright pivot standards, as above described, which contain the wheels, and possess the power of rotation; also their mode of construction and their application to any form of caror locomotive that may be used on railroads."

There is no probability that a car upon this plan will ever be essayed, and should it be, we are convinced that its career would end there. The idea that such a wheel would readily adapt itself to curvatures, is manifestly fallacious. It is to swivel round by the action of the two flanches of the wheel upon the rail, and that under the weight of the car and its burthen.

STOVE FOR HEATING IRONS FOR HATAERS, TAILORS, &c., Bartholomew W. Taber,

Falmouth, Massachusetts. This stove is intended to be used with anthracite as fuel, but other kinds may be burnt in it. The most convenient form is rectangular, the plates being, in general, of cast iron, and put together in the usual manner, The fuel is contained in a grate with front and bottom bars, such as are commonly employed in open fire places, and frequently in close stoves, there being a door in front by which the grate may be enclosed, and another above it for replenishing the fire. The receptacles for the irons to be heated are at each side of the fire, and consist of small compartments, like ovens, which are closed by doors that slide up and down; each of these compartments must be sufficiently long and deep to contain the goose, or pressing iron, which is to be laid upon its side within it, the handle standing out, so that when a door or shutter which closes the compartment is slid down, the handle of the iron is without, exposed to the air, there being two notches in the lower edges of each of these sliding shutters, to allow it to close over the two ends of the handle.

The distinguishing feature of this stove, as applied to the heating of irons is, that the irons are exposed to the direct action of the fire, there being bars at each end of the grate, which bars constitute the division between the fire and the compartments, so that the faces of the contained irons are exposed to it, as they would be if exposed against the front bars of an open grate, whilst, at the same time, they are confined within a small oven, or enclosed compartment, in which they will be rapidly heated.

PROTECTING TIMBER FROM DESTRUCTION BY WORMS AND DRY ROT, August Gotthilff, New York. -The patentee states, that he saturates the timber with either of the following articles, either alone or combined with common salt; or uses two or more of them so mixed, or combined, as may be preferred; that is to say, take common vegetable tar, pitch, the tar-like residuum from the manufacture of illuminating gas, in gas works where animal or vegetable oil, resin, a mixture of oil and resin, or any vegetable oleaginous or resinous substance is employed for the production of the gas, and melt or combine them together in such proportions as may appear best, adding, in most cases, to these resinous materials, and more especially when the timber to be saturated is of a very porous kind, from one-eighth to one-fourth part of their weight of common

from any of the above enumerated materials; this, however, will rarely be necessary. To effect perfect saturation, the timber and the resinous materials are placed together, in suitable metallic troughs, or tanks, the quantity of the resinous matter being sufficient to cover the timber; the whole is then submitted so a temperature of from three to four hundred degrees of Fahr. scale, for a term which may vary from one to twelve, or more, hours, dependant upon the size and nature of the timber; after which the redundant heated fluid is to be drawn off, when it will be found that the timber will be saturated throughout. The well known processes of exhaustion and pressure may be applied to promote the saturation, but it is not believed that this will ever be required.

He claims the application of the tar, pitch, and other analogous materials, obtained from vegetable substances, by the agency of heat, to the various kinds of timber, in the manner described, so as completely to saturate the same; using these various materials, in some cases, in combination with common salt; the saturating of timber with the vegetable products within mentioned, by submersing the timber therein, in a heated state, without, as well as with, the addition of common salt.

MACHINE FOR BREAKING AND DRESSING FLAX AND HEMP: Harvey Lull, New York. Upon a main shaft, the gudgeons of which are sustained in any suitable frame, I fix (says the patentee) two circular heads, which for an ordinary sized machine for hemp may be three feet in diameter, and three feet six inches apart. Between these heads there are to be fluted breaking rollers, which have their bearings near the peripheries of these heads, or in circular plates. These rollers may be of cast iron, or of wood covered with metal; they extend from one circular head to the other, and may be ten inches in diameter. They are fluted from end to end by deep angular flutes, each of which may constitute two sides of an equilateral triangle, and of these there are upon each roller usually ten in number. Two or more such rollers are placed at equal distance apart, with their teeth projecting beyond the edges of the plates in which their gudgeons revolve. Knives for dressing the hemp, or flax, extend across from head to head, there being one in advance of each roller, nearly in contact with it, and having its blade in the direction of the peripheries of the circular heads, and on a level with them, whilst they are strengthened by a strip on their backs at the under sides of them.

The breaking is to be effected by means of metallic plates, or slats, with the aid of the above-named fluted rollers, within the flutes of which they are to be received, their

conjoint action effecting the object. These slats may be of the same length with the rollers, four or five inches wide, and one fourth of an inch thick and they are to be so fixed that they may be made to pass to a greater oraless depth within the roller flutes, as the breaking proceeds; the rollers also must be made to revolve on their own axes, and both of these objects I effect in the following manner.

I prepare two flat circular plates, or hoops, usually of cast iron, which are to be of such size, and so attached to the frame of the machine, as that they shall surround. the fluted rollers, near each of their ends. One of these hoops is round on its inner edge, and the opening therein of such diameter as just to allow the fluted rollers to revolve, and to be carried round by the main shaft within, without touching it; this plate or ring, is about three inches wide.. The opposite plate differs from this first in being furnished with teeth on its inner edge, which mash into the flutes, or teeth, of the fluted rollers, which play with freedom in them. The effect of this arrangement is, that when the main shaft, carrying the cylinder of fluted rollers and knives, is made to revolve, the individual rollers will likewise revolve on their own axes.

The slats which are to pass between the teeth of the fluted rollers are received between the two last described hollow circular plates, extending from one of them to the other, and sliding in and out, in notches or groves prepared for that purpose, their planes pointing towards the centre of the main shaft. and standing in the middle of each of the teeth, by which the rollers are turned. The number of these slats may vary, but eight will usually answer the intended purpose; they occupy the upper portion of the machine, commencing about twenty degrees from its top on the feeding side, and extending about one-fourth of the way round.

I have said that these slats are made to slide in and out, as may be required, and this sliding I effect by making a projecting tongue on each end of them, which tongues are received into grooves upon moveble curved plates adapted to the inner sides of the hoops, or rings, by which the slats are sustained; the grooves, above named, form inclined planes, so placed that when the curved plates are made to slide back or forth within the circle, the slats simultaneously forced in or out: they are made to slide by means of a cranked lever attached to their ends, and which crosses the machine. Instead of tongues, there may be notches on each end of the slats, having inclined tongues, or fillets fitted into them; and the sliding of the slats also may be effected in other ways.

are

When this machine is used, the main shaft is to be made to revolve by any competent power; the tow or flax is to be held in the hand, or in a gripe made for the purpose, and fed in upon the revolving rollers, by which it will be carried under the slats, which by means of the cranked lever, are forced down as the breaking proceeds, whilst it is at the same time dressed by the knives, which separate the shivers from it, and clean it in a very perfect manner. When one end of the handful has been thus dressed and cleaned it is withdrawn, and the other end is fed in and cleaned in a similar manner. For flax the machine should be of smaller size than that designated; but considerable latitude may be allowed in this particular.

NOTES AND NOTICES.

Smoky Chimneys, It has often occurred to us that one very common cause of smoky chimneys, where no apparent cause can be discovered, arises from the practice of using boys to sweep them, and thus the sin against humanity is partly punished by a large amount of continuous annoyance. For a flue to draw well, it is essential that there should be only two openings into it-one at the bottom and the other at the top. Now, chimney flues are divided from one another by single courses of bricks in width, or half bricks, as it is technically termed. Those flues are built with lime mortar, which is an absurdity in the outset, as the heat of the fire restores the mortar to the state of quick lime, which falls out in powder, and leaves gaping chinks for misdraught between the bricks, destroying the continuity of the flue. To provide in some measure against this evil, the practice is to coat the inside of the flue with a composition of lime mortar with cow-dung, called "pargetting." This is, in fact, a luting to make the flue air-tight. The climbing boys, by frequent ascents, break the luting away, and the chimney, opening into chinks, produces an imperfect draught. This is an evil for which there is no remedy, except rebuilding the chimney. Were it the practice to use iron tubes built into the thickness of the walls, or better still-as more economical of heat to introduce hollow iron columns upon the face of the wall, covering them in the apartments with perforated screen partitions, the great source of evil would cease, and the still greater evil -the crime-the degradation of humanity-would cease also.-London and West. Review.

Quick Adventures of a Bale of Cotton-A bale-of cotton was shipped on board the Great Western, at New York, on the 6th ult.; arrived in King Road on the 22nd; was sent to the new cotton factory at Bristol on the 23rd; and on the 24th, part of it manufactured into yarn, was exhibited, at a public meeting of the inhabitants, as a specimen of the first cotton ever manufactured in that city.

Dr. Lardner and Animal Magnetism.-Dr. Lardner has recently taken occasion to announce his conversion to a full faith in the wonders of animal magnetism, on which he is delivering lectures at various scientific institutions, besides giving it the support of his powerful pen. He scruples not to

avow his belief that persons in the "sixth stage" of magnetism are gifted with the faculty of foretelling coming events. What a pity, then, the Doctor himself was not magnetised to this degree before he undertook to prophecy the fate of the Atlantic steamers! Another faculty with which the magnetised are gifted, is that of reading with the eyes shut; but it has not yet been stated whether they are able to read an article which ought to have appeared, but did not, in a scientific magazine. If this might be hoped for, it would be worth while to submit to be "treated" by the Doctor, taking care to have the last number of the Monthly Chronicle to practise upon. The reading of the missing article on "Ocean Steamers," would no doubt afford plenty of amusement, -especially to the magnetiser!

The Prepared Fuel again. The inventors of the celebrated" Jerusalem Coffee-House stove" have a new project on the anvil, for applying their prepared fuel to the generation of steam, and other similar purposes, by way, it may be supposed, of counterbalancing its utter failure for domestic uses. Query, if the death of any party had taken piace in consequence of full reliance on the assurances in the prospectus of the "new stove," as to the innocuous nature of the prepared fuel, would not the patentees have been indictable for manslaughter,