of the top and four sides of the stove are directed to be furnished with four plates of metal, which may vary in projecting depth from 1 inch to 12 inches, or more, according to the size of the stoves, and may be arranged in any directions, and at any angles with reference to the sides, that may be found convenient. The sides of the stove being furnished with any number of these plates, and arranged in any convenient manner, the stove is to be covered or surrounded with a casing of any suitable material, which, as it must touch the outer edges of the projecting plates, will form a number of zig-zag channels. Through these channels atmospheric air is conducted from below, through apertures made for that purpose. As metals of all descriptions are known to be good conductors of heat, the projecting plates, which are connected to the sides of the stove, soon become heated by the fire within, and the air being obliged to pass in narrow streams between these plates, soon becomes warmed, and, on arriving at the top, may be conducted off, through a pipe or flue, to any apartment that requires warming, or may be allowed to pass at once into the room which contains the apparatus. Straight or bent plates are equally applicable, and the apparatus may be also employed for diffusing heat derived from hot water, or from steam or gas. The patentee prefers that the projecting plates should be cast on to the sides of the stove, so as to form a component part thereof; but he does not confine himself thereto, "as they may be affixed to the side of the stove by hard solder." The air to be warmed is to be admitted to the apparatus through suitable holes or apertures made at the lower part of the casing, or in its bottom, and which air, in passing up the narrow channels, becomes warmed, and ultimately escapes at the upper part, through similar holes or flues, or may be conducted off to some other apartment, as before mentioned.

Pure atmospheric air may be supplied to the apparatus by means of pipes or flues leading from the outside of the building, and, by thus causing a constant draught, ventilate the apartment.

One of the principal advantages derivable from this invention is stated to be, "the increased extent of heating surface which is obtained by the application of the projecting plates, whereby a small stove may be made to give out as much, or more heat than one of larger dimensions, having plain sides, as at present made."

Claim." I claim the application of projecting plates, or pieces placed in zig-zag ranges, and at any angles, on the sides or surfaces of grates or stoves, or other appa

ratus for diffusing heat by radiation and rapid circulation of the atmosphere."

OSBORNE REYNOLDS, OF BELfast, IreLAND, CLERK, for certain improvements in covering streets, roads, or other ways with wood, and also in the means of enabling horses and other animals to pass over such roads, and other slippery surfaces, with greater safety than heretofore. Rolls Chapel Office, August 22, 1842.

These improvements are divided into two parts, and consist, firstly, in various improvements upon a former invention, for which Mr. Reynolds obtained a patent on the 27th of April, 1841, for "improvements in paving streets, roads, and ways," and secondly, in a novel method of making the shoes of horses and other animals, to prevent them from slipping, and giving them a firmer hold on the pavement.

"In order to form a firm, compact, and cheap pavement," the ground is first levelled and rammed hard, and also covered with sand if desirable. Upon this are laid boards, planks, beams, laths or slips, parallopipedons or other figures, such as may be formed by one cut either oblique or perpendicular from a plank of any breadth, and of any thickness not exceeding four inches. Blocks may also be used, formed similarly from round or unhewn timber. If desirable, a second, or even a third layer of boards may be placed on the first, embedded wholly or partially in cement, and nailed, or otherwise fastened together. Between the sides of blocks which are in contact, a few grains of gravel or other hard substance, not smaller than spheres whose diameter is th of an inch, may be interspersed, so that these grains may be partially embedded in each of two adjacent sides, and thereby strengthen their mutual support. To make the pavement water-tight, the blocks are surrounded with cement, and to unite the whole compactly together, the blocks are secured to the foundation planks, or to each other or both, by nailing or pinning each block to the mass already formed. "This method of fastening the blocks together," says the patentee, "is obviously different from any of the methods hitherto employed of securing a number together by means of pegs, pins, or dowels." To roughen the surface the inventor scatters upon it by the hand or some hand instrument, gravel or broken stone, screened so as to contain neither dust, nor sand, nor grains of any size less than that described above. This gravel is scattered in any quantity not exceeding 4 lbs. avoirdupois to the square-yard, and the operation is repeated often enough to keep the surface constantly rough; this repetition, combined with the use

of grains of a proper size, alone produces the whole effect desired without the accumulation of mud or dust, which always accompanies the use of gravel as it has been hitherto employed for this purpose.

To prevent horses from slipping, bars, ribs, or projections are formed on that part of the under side of horse-shoes, which is between the toe and the caulk.

The Claims are, firstly, To the method described of using boards for a foundation of wood pavement, also to the use of blocks of the forms described; together with the modes described of strengthening the whole by means of hard grains of gravel, nails of iron, or pins of wood; and further, the method described of roughening the surface continually by gravel or broken stone.

Secondly, To the improved method of constructing the shoes of horses and other animals, whereby they are prevented from slipping.

WILLIAM NEWTON, 66, CHANCERY-LANE, MIDDLESEX, CIVIL ENGINEER, for certain improvements in regulating the flow of air and gaseous fluids. Rolls Chapel Office, August 23, 1842.

These improvements consist in a "peculiar construction of apparatus, in which, upon the slightest increase of pressure from the air or gas which passes through the apparatus, the flow of the air or gas is restricted and regulated in a novel manner, until the extra pressure has ceased."

The working parts of the apparatus are contained within an outside metal casing, which is supplied with a moveable lid or cover. An annular moveable bell-shaped vessel is placed in the interior of the metal casing, covering an aperture by which the gas or air enters the bell-shaped vessel, and through which its throw or passage is regulated by means of the conical end of a hollow tube, which is suspended by means of a metal rod or chain from the inside of the bell-shaped vessel. The aperture for the admission of the gas or air is formed at the upper circular end of a metal cylinder, which is supported by an annular chamber or gallery, and when once placed in its proper situation, it remains stationary, and is prevented from moving laterally, or out of its position, by small blocks. The apparatus is supplied with water from above, by removing the lid or cover, and its level inside is seen by means of a glass tube outside. All the different parts of the apparatus that are to be filled with water are made to communicate with each other; and when the apparatus requires emptying, the water is allowed to flow out through an aperture to which there is a screw tap. The bell-shaped vessel is suspended by rods or chains from

the ends of levers, and the weight of the vessel, together with the hollow tube, is counterbalanced by weights at the opposite ends of the levers. Gas or air flows into the apparatus from a supply pipe, and passes up one annular passage into the upper part of the bell-shaped vessel, whence it passes down another annular passage, and finally escapes from the apparatus through a pipe. If the pressure of the air or gas into the apparatus is too great for the consumption, then it presses on the surface of the water, and against the domed part of the vessel; thereby causing the latter to rise and draw the conical end of the hollow tube up into the aperture, and contract the same, and not allow so great a quantity of gas to enter. When, by the issue of gas from the apparatus, the equilibrium or proper pressure is restored, then the vessel sinks again, and allows the conical end of the tube to descend also from the aperture, and permit the gas to enter.

Claim." I claim, first, the peculiar arrangement of apparatus herein shown and described, or any modification thereof; and, secondly, any apparatus for regulating the flow of air or gas, in which such regulation is effected by means of a conical plug, or the conical end of a tube, either hollow or solid, rising into the aperture through which the gas passes, and thereby closing, or partially closing the same, and preventing the air or gas from passing, as above described."

INSTITUTION OF CIVIL ENGINEERS. MAY 24, 1842. "Description of the Maplin Sand Lighthouse at the Mouth of the River Thames." By John Baldry Redman, Grad. Inst. C.E.

The paper commences with an enumeration of the various channels and sandbanks at the mouth of the Thames, with the floating lights, beacons, and buoys marking the entrances of the Channel, and gives the objections to floating lights and the reasons for selecting the Maplin Sand as the position for a fixed lighthouse.

In the year 1837 a survey was made by Mr. Walker, the engineer to the Trinity House, and by boring it was ascertained that the first 6 feet of the sand was close and compact, but below that for 20 feet the boring rod went more easily as it descended, and it was found that it became mingled with argillaceous earth as the depth increased.

It was then decided to use for the foundations Mr. Mitchell's screw moorings, and in 1838 the patentee, under Mr. Walker's directions, commenced fixing nine cast-iron

screws of 4 feet diameter, so as to form an octagon with one screw in the centre: attached to each of these screws was a castiron pile 5 inches in diameter and 26 feet long, which was inserted into the sand 21 feet below low-water mark. On account of the constant shifting of the sand from around the piles it was determined to place a raft or grating of timber around and between them: the surface of the raft was covered with faggots of brushwood well fastened to the timbers, and upon them was deposited 120 tons of rough Kentish ragstone, by which the raft was secured in its situation, and after a time no farther changes occurred in the level of the surface of the sand.

In the summer of 1840 the superstructure was commenced: it consists of nine hollow iron columns or pipes, curved at the top to a radius of 21 feet towards the centre; they were secured upon the piles, and two series of continuous circular horizontal ties bound them together, while they were connected with the centre column by diagonal bracesall of wrought iron. Upon these columns is built a wooden dwelling for the lightkeepers, in the upper part of which is placed a French dioptric light of the second order, its centre being 45 feet above the mean level of the sea, and at that elevation can be seen from a ship's deck at a distance of nine or ten miles; a bell is fixed on the gallery which is sounded by machinery at intervals during dark and foggy nights.

The communication gives all the details of the dimensions and the mode of fixing the cast-iron screws and piles made by Messrs. Rennie-the iron-work by Messrs. Gordon of Deptford-the woodwork by Messrs. Gates and Horne of Poplar, and the lantern by Messrs. Wilkins-and the whole is illustrated by a series of drawings which fully describe this useful construction, which has hitherto withstood the most violent attacks of the sea to which it is exposed.

In answer to questions from the President, Mr. Wilkins stated that he had been in the Eddystone and the Maplin Sand lighthouses during severe gales of wind: that, as might be conceived from the nature of the construction, the latter building was more affected than the former by the striking of heavy seas the motion appeared to be more like torsion than simple vibration, which he attributed to the waves striking the ladder and its projecting stage, and thus tending to twist the upper part. Still the motion was not such as would cause injury to the building.

The President pointed out two diagonal braces extending downward from the end of the ladder stage to the piles on either side,

which had been introduced in order to counteract the twisting described by Mr. Wilkins. In constructions of this nature it was of importance to oppose as little resistance as possible to the seas, especially in the upper part of the building, a system of bracing had therefore been adopted which consisted principally of two series of continuous circular horizontal ties between the piles at the several heights of 6 feet and 15 feet above low-water mark of spring tides. From the external ring of piles two sets of diagonal stays extended to the centre pillar, forming strong triangular trusses in the direction of each pile, and two sets of horizontal stays stretched between the piles and the centre pillar at the levels of the circular bands. The amount of direct vibration was very small, and he did not conceive that the twisting motion which had been described was sufficient to warrant the introduction of diagonal braces, which would materially augment the surface upon which the waves would act.

Mr. Vignoles directed the attention of the meeting to the system of diagonal bracing between the piles which had been adopted at the Port Fleetwood lighthouse; he apprehended that as the principal force of the waves would be exerted against that part of the, structure which was above the highwater level, the diagonal braces extending between the upper part of the piles and the level of low-water were preferable to the horizontal continuous bands of the Maplin Sand lighthouse, although assisted by the system of radiating central truss braces which it possessed: he conceived that both buildings were strong enough for the purposes for which they were constructed, but he preferred the mode of bracing adopted in the Port Fleetwood house, the vibration of which he knew to be very small, although situated in an exposed position where the rise of tide is 30 feet.

Mr. Donkin observed that there could not exist a doubt of the introduction of diagonal braces rendering the building stronger; how far they were necessary or might be prejudicial in offering additional resistance to the passage of the waves should be well examined before adopting them. He considered the position of the suspended ladder decidedly objectionable, as any torsion caused by the waves striking it must tend to dislocate the fibre of the material of the piles and to fracture them.

Mr. Farey believed the construction of the Maplin Sand house to be better adapted than the Fleetwood house for resisting the direct action of waves, but the diagonal bracing of the latter enabled it to withstand torsion better than the hoop bracing of the former. He inquired why the lower part of

the light-keeper's house was made conical, as he apprehended that it would receive a heavier blow from a wave than if it had been flat.

The President replied that the main body of the waves seldom or never rose so high as the bottom of the house, and that the conical form allowed the air and spray to rise up and be guided off without affecting the building, as it would do if the bottom was flat.

With regard to the torsion, that had only been felt at first when the ladder extended too low down and received a constant succession of blows from every wave, which naturally communicated a vibration to the whole structure: the ladder was now shortened and nothing of the kind was felt; the waves scarcely, even in the roughest weather, struck the suspension stage or the boat. He preferred the continuous horizontal bracing, which bound all the piles firmly together like the staves of a barrel; and from observations he had made he believed the amount of vibration to be greater in the Port Fleetwood lighthouse than in that at the Maplin Sand.

In answer to a question from Mr. G. H. Palmer, the President said that at present there was not any indication of a change in the condition of the cast iron from its contact with the salt water.

Professor Brande was unable to give any additional evidence on the observed facts connected with the change suffered by cast iron exposed to the action of salt water, or in mines and in various other positionsfrom experiments which he had made, he was led to believe that many of the appearances observed in the changes of cast iron arose rather from a peculiar mechanical combination of the molecules, than from a difference in the chemical constitution of the metal no difference could be detected by analysis in the metal which had undergone change and that which had not.

It should be remarked that the contact of two metals was not essential to cause galvanic action; a film of oxide upon the surface of the body of metal formed a very active galvanic pile: hence arose the necessity for preventing oxidation by proper paints or varnish before using pieces of cast iron in exposed situations.

Mr. Farey observed that in the early engines constructed by Woolf in Cornwall, in which the packing segments were of gunmetal and the body of the piston was of cast iron, wherever the two metals were in contact the iron was turned to plumbago: this had been particularly observed where highpressure steam was used: it might be a question whether the temperature of the steam,

and the quantity of mineral water carried over with the steam by the large amount of priming of the engines in that day, had not materially contributed to produce the effect.

Mr. P. Taylor believed that the temperature of the steam had not any connexion with the subject: in the metallic packing of steam pistons of low-pressure marine engines, which he had constantly under repair at Marseilles, wherever the wedge-pieces were of gun-metal, the backs of the castiron segments were converted into plumbago, whilst those surfaces of cast iron which were ground together and worked against each other remained unchanged: the same might be said of the rubbing surfaces of cast iron against gun-metal; it appeared therefore that the formation of an oxide was necessary to commence the change. repudiated the use of cast iron in situations where these changes were to be apprehended; he would employ wrought iron, as although that did become oxydized, it retained its relative strength to the last, whereas cast iron when changed into plumbago, retained its bulk but lost nearly all power of cohesion.

He

Mr. John Taylor said that in Cornwall the cast-iron pump-trees exposed to the action of mine water were very speedily destroyed; and even although 14 inch thick they could be cut to pieces with a knife when first taken out of the pit. The air-pump buckets of steam-engines, in which the body was of cast iron and the valves of gun-metal, formed the most perfect kind of galvanic apparatus; they should be made entirely of gun-metal.

In manufactories of vinegar and pyroligneous acid the decay of cast iron was very rapid.

Mr. Glynn attributed in a great degree the rapid decay of cast iron in coal mines to the presence of sulphuric acid evolved from the pyrites.

Mr. Philip Taylor agreed with Mr. Glynn: even copper pipes were rapidly destroyed in the bilge-water of vessels which always contained much sulphuretted hydrogen-he recommended the use of stout lead pipes in such situations; they would be found much more durable.

Mr. Davison had found it necessary to substitute gun-metal gratings for the castiron ones at Messrs. Hanbury's brewery, as although they were inch thick they had been entirely destroyed in four years.