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and in all this, there was nothing but a very natural result of the spiral form; but nevertheless, I was very much pleased to see it. In repeating the same experiment with the screw of 8 feet spiral, I found quite a different result. The wind, instead of rushing along the blades, as in the former case, was blowing with violence at right angles to the axis of the screw, and was not at all felt at its extremities. Here we had exemplified the very effect produced by the screw propeller of the Great Britain; the water is thrown off at right angles to the axis of the propeller, in the same way as the wind was blown off by my little screw.

It is of no use, however, finding fault unless one is prepared with a remedy. I beg therefore to propose a new method of screw propelling, which I feel confident would prove capable of propelling a vessel with perfect safety at a much greater velocity than any yet obtained.

I propose to construct a screw of 100 feet long with four blades of 12 inches deep, and 2 feet spiral; I would enclose it in a tube within which it should revolve freely; and this tube should be laid along the keel of the vessel, and the ends of this tube should pass through the stem and stern posts. The fluid would of course rush through the apertures, and would fill the tube throughout. The screw being enclosed therein, would have the same power of propulsion as if it were exposed to the open water, while it would be entirely protected from all external dangers. The tube might be made of wood, which would answer perfectly well.

Let us now proceed to speculate upon the power of a screw of 100 feet long with four blades of 12 inches deep and 2 feet spiral.

It is obvious that a screw of this description would have a firm hold upon the water, consequently an immense power to propel, as there would be no less than 400 spiral faces to draw the fluid.

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believe it is not at all improbable that this screw could be made to revolve more than 1000 revolutions in a minute. Being enclosed in a tube, the waves of the sea could not interfere with its velocity, and its motion would be continually even and regular; consequently the engine could suffer no injury from the unequal motion of the propeller as when it is exposed to the force of the waves, which must necessarily be a very great impediment to the progress of the propeller, and in some instances render it quite inoperative. I am, Sir,

Your obedient servant, L. GACHET. Coggeshall, Essex, Nov. 27th, 1845.

LIGHT AND

ELECTRICITY-PROFESSOR FARADAY'S DISCOVERIES.

At a meeting of the Royal Society, held on the 27th of November, a paper by Mr. Faraday, "On the Magnetisation of Light, and the Illumination of Magnetic Lines of Force," was read.

For a long time past the author had felt a strong persuasion, derived from philosophical considerations, that among the several powers of nature which in their various forms of operation on matter, produce different classes of effects, there exists an intimate relation; that they are connected by a common origin, have a reciprocal dependence on one another, and are capable, under certain conditions, of being converted the one into the other. Already have electricity and magnetism afforded evidence of this mutual convertibility; and, in extending his views to a wider sphere, the author became convinced that these powers must have relations with light also. lately his endeavours to detect these relations were unsuccessful; but at length, on instituting a more searching interrogation of nature, he arrived at the discovery recorded in his paper, namely, that a ray of light may be electrified and magnetized, and that lines of magnetic force may be rendered luminous.

Until

The fundamental experiment revealing this new and important fact, which establishes a link of connexion between the great departments of nature is the following:-A ray of light issuing from an argand lamp is first polarized in the horizontal plane by reflection from a glass mirror, and then made to pass for a certain space through glass composed of silicated borate of lead, on its emergence from which it is viewed through a Nichol's eyepiece, capable of revolving on a horizon

PROFESSOR FARADAY'S DISCOVERIES.

tal axis, so as to interrupt the ray, or allow it to be transmitted alternately, in the different phases of its revolution. The glass through which the ray passes, and which the author terms the dimagnetic, is placed between the two poles of a powerful electromagnet arranged in such a position as that the line of magnetic forces resulting from their combined action shall coincide with, or differ but little from, the course of the ray in its passage through the glass. It was then found that if the eyepiece had been so turned as to render the ray visible to the observer looking through the eyepiece before the electric current had been established, it becomes visible whenever, by the completion of the circuit, the magnetic force is in operation; but instantly becomes again invisible on the cessation of that force by the interruption of the circuit. Further investigation showed that the magnetic action caused the plane of polarization of the polarized ray to rotate; for the ray was again rendered visible by turning the eyepiece to a certain extent; and that the direction of the rotation impressed upon the ray when the magnetic influence was issuing from the south pole, and proceeding in the same direction as the polarized ray, was righthanded, or similar to that of the motion of the hands of a watch, as estimated by an observer at the eyepiece. The direction in which the rotation takes place will, of course, be reversed by reversing either the course of the ray or the poles of the magnet. Hence it follows that the polarized ray is made to rotate in the same direction as the currents of positive electricity are circulating, both in the helices composing the electromagnet, and also as the hypothetical currents which, according to Ampère's theory, circulate in the substance of a steel magnet. The rotary action was found to be always directly proportional to the intensity of the magnetic force, but not to that of the electric current; and also to be proportional to the length of that portion of the ray which receives the influence. The interposition of substances which occasion no disturbance of the magnetic forces produced no change in these effects. Magnets consisting only of electric helices acted with less power than when armed with iron, and in which magnetic action was consequently more strongly developed.

The author pursues the enquiry by varying in a great number of ways the circumstances in which this newly discovered influence is exerted; and finds that the modifications thus introduced in the results are all explicable by reference to the general law above stated. Thus the effect is produced, though in a less degree, when the polarized ray is

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subjected to the action of an ordinary magnet, instead of one that derives its power from a voltaic current; and it is also weaker when a single pole only is employed. It is, on the other hand, increased by the addition of a hollow cylinder of iron, placed within the helix, the polarized ray traversing its axis being then acted upon with great energy. Helices act with equal power in any part of the cylindric space which they enclose. The heavy glass used in these experiments was found to possess in itself no specific magneto-inductive action.

Different media differ extremely in the degree in which they are capable of exerting the rotary power over a polarized ray of light. It is a power which has no apparent relation to the other physical properties, whether chemical or mechanical, of these bodies. Yet, however it may differ in its degree, it is always the same in kind; the rotation it effects is invariably in one direction; dependent, however, on the direction of the ray and of the magnetic force. In this respect it differs essentially from the rotary power naturally possessed by many bodies, such as quartz, sugar, oil of turpentine, &c., which exhibit the phenomena of circular polarization; for in some of those the rotation takes place to the right, and in others to the left. When, therefore, such substances are employed as dimagnetics, the natural and the superinduced powers tend to produce either the same or opposite rotations; and the resulting effects are modified according as they are cumulative in the former case, and differential in the latter.

In the concluding section of the paper the author enters into general considerations on the nature of the newly-discovered power of electricity and magnetism over light, and remarks that all these powers possess in common a duality of character which constitutes them a peculiar class, and affords an opening, which before was wanting, for the application of these powers to the investigation of this and other radiant agencies. The phenomena thus brought to light confirm the views entertained by the author relative to the constitution of matter as being spheres of power, for the operation of which the conception of a solid nucleus is not necessary; and leads to the presumption that the influence of magnetism on bodies which exhibit no magnetic properties consists in producing in them a state of electric tension tending to a current; while on iron, nickel, and other bodies susceptible of magnetism, currents are actually established by the same influence.

RECENT AMERICAN PATENTS.

[From Mr. Keller's Abstracts in the Franklin Journal.] IMPROVEMENTS IN THE PRINTING PRESS. John L. Kingsley.-The patentee says-" In my improved press the inking apparatus, and that for making the impression, are in their general construction, similar to those employed in the most improved machines, but they are so modified and arranged as to adapt them to an entirely new apparatus for conveying the sheet to the required positions for printing them on both sides, or what is technically called perfecting the sheets ; which is done before the sheets leave the gripper, by which they are deposited correctly in a pile ready for drying. By this arrangement, one person is required to feed the machine by supplying the sheets to be printed, the press being actuated by any adequate power.

when closed, in combination with the closer and opener, substantially as set forth."

"In a machine thus arranged, one half the labour of feeding required in the best registering machine with which I am acquainted, namely, that of Tuft's of Boston, is saved, and with the employment of two persons at the feeding board; his press affords only about six hundred impressions in an hour, whilst, as my machine takes two impressions to one sheet supplied, and the printed sheet is deposited without interfering with the feeder or feeding, it may be run at any speed which allows time merely for the inking and the supply of sheets, and may consequently make from twenty to twenty-five hundred impressions in an hour. My machine secures a perfect register, as the sheet which has been fed in the gripper does not leave them until it is perfected, when it is deposited as hereinafter described."

Claim.-"What I claim therein as new, is the arrangement of the grippers combined with the carrying belts, by which I am enabled to carry in the paper, hold it, and retain it until it is perfected, by which it prints it on both sides and then deposits it; the operations being effected by so combining the sheet apparatus with the inking rollers as to give the carrying belts and grippers an intermitting progressive movement, as described.

"I also claim in combination with the printing apparatus, the so arranging of the carrying belts as to return the sheets of paper which have been printed on one side at nearly the same level which they occupied when they received the first impression, they being in both cases at the proper elevation for giving the impression as described.

"I claim, likewise, the manner in which the grippers are made to open and close by means of a spring operating to force and hold them open, and bolts for holding them

MACHINE FOR BACKING BOOKS, FOR BOOKBINDERS. William Laighton.-The patentee says "The operation of backing consists in giving that roundness or convexity to the back of the book which is necessary to prepare it for the reception of the covering of leather or other material. This process is usually performed by confining the book after it has been stitched and cut, between suitable boards or plates of metal, which are pressed firmly together by means of screws, and the back is then hammered into the desired form. In my machine, the book to be backed is confined between two plates, or jaws of iron, which are made to clasp it firmly, as if between the jaws of a vice, and these plates are so arranged as when closed to constitute a carriage, which, by means of a rack and pinion, is moved on in a straight line, so as to bring the back of the book against a roller, or against a block of iron, or other metal; when a roller is used it is made hollowing or concave on its periphery, and is so adjusted as to force the back of the book to assume the desired convex form, leaving it perfectly straight from end to end, and giving to it an equal convexity in all its parts. When, instead of the concave roller above named, I use a block of iron or other metal, which is made to occupy the place of the roller, the said block has that side of it which is towards the back of the book made concave, or hollowing lengthwise, and the back of the book as it is passed along being made to press against the block, receives the desired form; this latter manner of forming the instrument possesses some advantages over the roller, and will probably be generally preferred.

Claim.-"What I claim therein as new, is the manner herein described of causing the back of such books to be carried along against a fluted roller, or block of metal, whilst they are confined between the jaws of what I have herein denominated the backing irons, the respective parts of the said machine being arranged and operating substantially as herein fully made known."

APPARATUS FOR WORKING A VERTICAL FORGE HAMMER. George E. Sellers.The essential feature of this invention is, for working the hammer by means of two rollers, that receive motion from a steam engine, or other motive force, one of which has its bearings in permanent, and the other in moveable boxes connected with a togglejoint or other lever, so arranged as to force this roller towards the other, and gripe a

RECENT AMERICAN PATENTS.

square rod on the hammer to lift, and then separate them to liberate it-the toggle joint lever being connected with the roller by means of a powerful spring; and the mechanism that operates the toggle so arranged as to enable the attendant to regulate the play of the hammer at his discretion, to strike a light or heavy blow, as the condition of the iron may require.

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Claim." What I claim as new, is the manner of operating upon the lifting rod by means of the friction drums, one of which is made to advance to, and to recede therefrom, by being placed on a sliding frame which is operated upon by a toggle joint, under an arrangement of parts substantially the same with that herein described. I also claim the manner of arranging the respective levers, the catch, the cam wheels, and their appendages, so as to be operated upon by the lines and chains attached to the said levers, substantially as described.'

BUCKLE FOR CONNECTING STRAPS. Kasson Frashure.-This buckle fastens the straps together without a tongue, and is called by the patentee the "Angular Box and Grooved Roller Buckle." The lower plate, which is attached to one of the straps, forms with the upper one an angle, so that at one end they are nearer together than at the other; this constitutes what is termed in the specification the angular box. The upper surface of the lower plate of this box is grooved, and on it runs a grooved roller, the grooves of each fitting into each other like cogs. The strap to be fastened is passed between the top plate of the angular box and this roller, so that the more the strap is pulled the tighter it is squeezed by the turning of the roller against the upper plate. The angular box is provided with the requisite loops for retaining the straps in their proper directions. The roller is connected with the lower grooved plate of the angular box, by a strap which embraces the middle part of the roller, reduced in size for that purpose, and passes down through a slot in the plate and is there provided with a plate.

IMPROVEMENT IN BUCKLES OR APPARATUS FOR CONNECTING STRAPS. Charles F. Beverley.-This differs from the preceding only in the use of a lever for the roller, so arranged, that, as the part which bears upon the strap, and which is notched for that purpose, is drawn forward by the strap, a catch on the upper surface of the lever is received in a lower tooth of an inclined rack attached to the grooved bottom plate, and thus the lever is caused to gripe the strap the tighter.

COMPOSITION OF MATTER FOR LUBRICATING THE RUBBING SURFACES OF MACHINERY. Increase S. Hill and Joseph

395

Dixon. The patentees say, "Our composition consists chiefly of zink, (which as is well known belongs to the class of cheaper metals,) hardened by being compounded with what we denominate a hardening composition.

"This latter composition is formed of the following metals, mixed in a state of fusion in the proportions hereinafter specified, viz. fifteen parts of tin to thirty-five parts of copper.

"This composition in a state of fusion is to be mixed with molten zink and tin, (although tin is not absolutely essential) in the proportion of the two parts of the said hardening composition, of nineteen parts of zink, and from three to five parts of tin, according to the peculiar purpose for which this composition is to be used, the tin specified to be added last, having the tendency to render the compound when cold more or less ductile, according to the quantity of the same incorporated therewith. The metal formed without the addition of the last named proportion of tin, when broken, will have the appearance of cast steel, of coarse quality, but the addition of tin will make it stronger, and cause it to be finer in grain until four parts of the same will be added, when the appearance of the metal, on its being broken, will resemble the finest cast steel, and more closely resemble the same than any other metal.

"The great strength of the composition, combined with a certain degree of softness which it possesses, renders it highly useful in the construction of bearings for rubbing surfaces of machinery, as it is capable of resisting for a great length of time, the effects of wear and attrition. The large proportion of zink used in forming the compound renders its use in the mechanical arts much less expensive than the metal ordinarily employed for these purposes, the cost being much less than any other composition in which copper and tin are the principal metals."

IMPROVEMENTS IN THE SYPHON FOR TRANSFERRING LIQUIDS. George Johnson. -The first improvement claimed is for charging single or double syphons by means of a bulb connected with the upper part or bend of the syphon, the bulb being of sufficient capacity to contain as much water as will fill the syphon. The second improvement claimed is for shielding syphons against reaction when one leg is to be used in warm water, by means of a shield or sleeve surrounding the leg of the syphon. And the third improvement claimed is for the manner of combining the bulb with a double syphon by means of a tube passing from the inner syphon through the neck of the bulb which is of sufficient capacity to form the communication with the outer syphon around this tube.

THE CONSTRUCTION OF RETAINING WALLS AND DRAINAGE OF EARTH WORK. [Abstract of a Paper read before the Institution of Civil Engineers. By Thomas Hughes, Esq., C.E., with Discussion thereon.]

The object of this paper was stated to be not to enter upon the causes of slips, but, to give a description of the employment of Watson's drain pipes, and of their application to two railway banks, in the neighbourhood of London.

These pipes are made with numerous apertures, which are small externally, and enlarge inwardly. See Mech. Mag. vol. xli. p. 336. Apertures of this form are not liable to become clogged; for the sides, being cut away, allow whatever enters to pass freely into the pipe. Without apertures, no pipes can be of much use in draining, though they may serve to convey away any water that happen to enter them by the joints; and common apertures are so soon choked, that they are of little use.

It had not been thought desirable to make these drain pipes of common clay, since, at a trifling extra expense, they can be made of the iron-stone clay, which abounds in Staffordshire and is acknowledged to be of very superior strength and durability. The pipes are also made with sockets, and are thus safe from the risk of displacement.

In March, 1844, Mr. C. H. Gregory, the resident engineer of the London and Croy. don Railway, permitted an experiment to be tried upon a piece of bank, selected as the worst part of the line. The spot chosen was near the Sydenham station, at the side of the up-line. The mode of proceeding was as follows:-A longitudinal trench, 4 feet deep, was dug on the crown of the bank, at a few feet from the edge; and other trenches, about 30 feet apart, descended from it to the open drain, by the side of the permanent way. The drain pipes were then laid in, and the clay, which had been dug out of the trenches, was laid over the pipes. As great advantage is, in such cases, to be expected from ventilation, an occasional upright pipe rises from the longitudinal line of pipes to the surface. An interval of dry weather causes the soil round the pipes to crack in every direction, and thus opens numerous fissures for the passage of water to the drain pipes. This is particularly the case with clay; which, though generally presumed to be unfavourable for drainage, is, in this way, as easily managed as any other soil. This may be readily tested by exposing clay, which has not been manipulated, to a drying atmosphere for a few hours.

This picce of bank has not slipped since it was drained; but, as it is only 120

feet in length, and 20 feet in height, it is wished more particularly to call attention to a bank, a quarter of a mile in length, and rising upwards of 60 feet in height, having higher ground behind it. This bank is on the down-side of the line, between Chalk Farm bridge and Primrose Hill tunnel, near the London terminus of the London and Birmingham Railway. It was in a very precarious state, when placed in the hands of the author, in June, 1844. The soil was the London clay, and the trenches to receive the pipes varied in depth from 3 feet to 6 feet; the workmen being guided in this respect by the appearance of the ground as it was opened. descending trenches were cut about 80 feet apart. The work has proved very satisfactory, and no repairs have been required since it was finished.

The

It was contracted for at 2001., and, as the length of pipe laid was 2,600 feet, it is at the rate of 1s. 6d. per foot, including every charge.

The author expects that this method will be found much more efficacious than either bush or stone draining, as such drains soon become clogged in heavy land, and never can possess the advantage of a circulation of air.

It will be recollected, that the close of the autumn of 1844 was extremely wet, and, as this work was executed in June, it has been well tried.

Retaining walls are frequently found to suffer severely from want of drainage, and, perhaps, no one more so than that of the Euston incline, London and Birmingham Railway. The application of these drain pipes was permitted on part of this wall, and every facility was given to the undertaking by the resident and consulting engineers.

It was necessary to bore through the wall, and several feet behind it, in order to insert the pipes; which, for this purpose, were made of cast iron, in lengths of four feet each, and were about 3 inches diameter. Boring through the wall was accomplished by a machine (which will be described on a future occasion); and, at some spots, considerable quantities of water issued instantly; but, in other places, no water appeared for several days, or until rain had fallen; and some of these borings were observed to dry up wet places, which showed in the wall at the distance of several feet. This result was expected, from the admission of air causing the earth to dry, and to crack, all round the pipes; thus opening channels for the admission of water into them; and, after a heavy

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