The ornaments, formed by the methods above described, may be allowed to retain a certain degree of the pliancy of the leather, or have a hardness given to them, equal to that of wood, or plaster, by causing them, when sufficiently dry and warm, to absorb a solution of gum-lac, dissolved in spirits of wine, or of resin, in spirits of turpentine, or merely a solution of glue. All the cavities, in the back of the design, must be filled up with paper, saw-dust, or pulverized cork, mixed with glue or hot resin.

When the embossed or basso-relievo ornaments, or devices, are used for the panelling of rooms, in imitation of carvings, the pieces of embossed leather should be united, so as not to shew the junctions.

It is obvious that these raised or embossed products may be painted, gilded, or silvered, (when rendered impervious by gum-lac or any suitable resinous substance,) or they may be painted to represent wood, marble, or other materials.

The patentee claims, firstly, the improved process, manner, or method, herein before set forth and described, of obtaining copies or fac-similes of pieces of sculpture, carvings, models, castings, and other raised figures, in bassorelievo, on leather or skins of animals; and the means used therein; particularly the application and use of saw-dust, or other powdered or finely-divided substance, for the purpose of forcing the skins into the cavities of the dies or moulds; and secondly, the improved mode or method of making or forming the moulds, dies, or matrices, or apparatus, also herein described, as connected with the above process of producing basso-relievo devices on skins of animals.-[Inrolled in the Rolls Chapel Office, December, 1839.] Specification drawn by Messrs. Newton and Son.

SIR,

ON WOOD PAVING.

(To the Editor of the London Journal of Arts, Sciences, &c.)

I feel some diffidence in laying before you a plan, which has lately occurred to me, for giving a firm foot-hold to horses

upon wood pavements, knowing, as I do, that the letters which appear in your valuable publication, are generally from gentlemen distinguished, for their talents, in the scientific world; but should my suggestion meet with your approval, I shall receive more satisfaction from its appearing in a work, which was the first to bring before the public the applicability of wood to paving roads, and has since traced the various improvements made in this now all-engrossing subject, than if it were published in any other journal.

At present there seem to be three methods proposed, to obviate the inconvenience of horses slipping upon wood pavement. The first is by grooving the upper surface of the blocks, or shaping them so as to leave spaces between the blocks when laid down. This system has evidently two objections:-Firstly, mud and dirt are harboured in the grooves and spaces, which, working up in wet weather, render the wood extremely slippery; and secondly, the heavy pressure of waggons and other vehicles passing, is very likely to crush the end fibres of the wood, and cause the grooves thereby to be filled up, and require constant cutting or grooving, by which the substance of the block is gradually diminished. The second method, is substituting a shoe, with ribs and other projections, in place of the ordinary horse-shoe, which, if it be no inconvenience to the horse, is certainly an innovation not likely to be generally adopted. The third method, is strewing on the surface of the road-way gravel or sand, the expense of doing which, and the dirt it would occasion, if done, are obstacles almost sufficient to balance its usefulness.

The plan I would submit, as an improvement to the foregoing, is to lay down bars of cast-iron, in lines parallel to the curbstone, with knobs or small projections, about an inch apart, on their upper surface. Grooves must be cut between the lines of blocks to receive the indented bars, the knobs of which, when laid down, should project about a quarter of an inch (more or less) above the paving. By these means, horses will be enabled, with their present shoes, to get a good hold of the ground, whilst, at the same time, the other parts of the pavement may be made perfectly smooth. The number of rows of bars must be regulated according to the width of the road-way; for instance,-if the way be wide enough to admit of two carriages going abreast, I would have nine bars laid down, at about four inches apart, in the middle of the road, and nine in the centre of the space, be

tween the middle and the curb-stone; this would be width of surface sufficient for a pair of horses to trot over, while the carriage would travel on the smooth wood without the least jar. An advantage, besides saving of material, would be derived, by making the safe footing partial, as the driver must, of necessity, keep on his proper side of the road when running at any speed. The bars, which may be half an inch wide, should be cast with prongs projecting downwards, in order to fix them when inserted in the pavement.

With a wish to remedy the evils of wood paving, and at the same time preserve that boon which only the inhabitants of a crowded London thoroughfare can appreciate, I submit my suggestion to the attention of your readers, which, should it be found impracticable, may at least bring some more able person to consider the subject.

I am, Sir,

Your obedient humble Servant,

A SUBSCRIBER.

Scientific Notices.

NEW MEANS OF INCREASING THE SENSITIVENESS OF DAGUERREOTYPE PLATES.

BY M. BARNARD.

The author prepares the iodized plate according to the ordinary method employed by M. Daguerre; after which he exposes it, for a half a minute, to the action of chlorine, mixed with common air, in such proportion that it may be inhaled without any very painful sensation. The plate then becomes so sensitive, that on placing it in a dark room, with an aperture similar to that employed for portraits in miniature, an impression is produced in the short space of time necessary for removing and replacing the screen. The drawing is completed, by mercury, in the ordi

nary manner.

A plate, thus treated with chlorine, becomes, when exposed to the light, of a very deep violet color, nearly black. The mercury does not become tarnished immediately, and in this state, the picture is even more beautiful than when it has been washed with

VOL. XXII.

N

the hyposulphate of soda; but this washing is necessary for its preservation.

According to the author, the lights and shadows are more distinct by this process than by the ordinary method. The proportion of chlorine, necessary for producing the effect, is very small; an excess of chlorine must be carefully avoided. It is almost unnecessary to add, that no light must, on any account, be admitted during the operations.-Bibl: Univ.

COLORING PHOTOGRAPHIC PICTURES.
BY M. LECHI.

M. ARAGO has presented to the Academy of Sciences, in the name of M. Lechi, some photographic pictures, colored after being formed. This coloring is effected in a very simple manner; it consists in depositing successive uniform layers of color on each part of the picture, which is removed, almost immediately afterwards, by passing the plate through hot water.

What remains of the color, after this ablution, does not seem, in the least, to injure the appearance, or alter the form of the image. The effect is different from that obtained by coloring an image upon paper, in which, if a uniform layer of color be put on those parts where the tone of color is the same, it will always be seen that the shadows have, at first, been black. In the specimens, presented by M. Lechi, the shadows, on the contrary, seem to result from the application of several layers of the same color. Thus it seems, that those parts of the picture which were at first black, retain, after being washed, a larger proportion of coloring matter than the lighter parts.

REPORT OF TRANSACTIONS OF THE INSTITUTION OF CIVIL ENGINEERS.

(Continued from page 59, Vol. XXII.)

"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 sand-banks 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 cast-iron 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 further 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 braces-all of wrought-iron. Upon these columns is built a wooden dwelling for the light-keepers, 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 wood-work by Messrs. Gates and Horne, of Poplar; and the