by means of a small chain, and may be fixed and removed with the utmost facility.

The figures C and D, represent the spanner as closed, when the

two ends stand even. The jaws are still separated to a small distance, to allow of strengthening the fixed bar, by forging it in the bracket-like form seen in the drawing.

On the means of Propelling Boats on Canals. By MR. DAVID GOKDON, of London. Communicated by the Author, in a letter to the Editor of the Repertory of Patent Inventions.

SIR,-Should you consider the following particulars of a voyage I lately made from London to Manchester, in a steam boat constructed on the plan for which I obtained a patent, (a copy of the specification of which you inserted in the 1st vol, of the present series of your work,) likely to prove of interest to the readers of the Repertory, you will, perhaps, allow them to be inserted in your ensuing number. If increased speed, certainty, and the saving of expenses, be objects to canal proprietors, I feel very confident that the present invention, if judiciously adopted, will prove of great importance to them.

The objections to steam boats on canals, have, hitherto, been the projections of the wheels, the injury done to the sides and bottom of the canal, by the agitation of the water, from the blow given to it by the paddles, and by the paddles occasionally striking and destroying what is called the puddling. In my boat, these are obviated by having the paddles near the stern, within the line of the bottom and sides of the boat, and completely enclosed, both under, and at the sides of the paddles, with a plate of sheet iron, which not only prevents any possible agitation of water from the paddles, but also protects the wheels from being injured by coming in contact with the bottom or sides of the canal, by striking against the locks or bridges, or by being struck in passing, (a very frequent occurrence) by the other boats in the canal.

That my steam boat would cause less injury to the sides of the canal than even any other boat displacing the same quantity of water, and propelled with equal rapidity, I expected, because the principal injury to canals arises from the wave which follows the boat, to fill up the hollow it leaves; and the paddles of my boat drawing a quantity of water from considerably before them, and discharging it behind, fills up that hollow. The water, in fact, behind my boat, instead of being in one following wave, is all broken, and makes 15 to 20 small waves.

In going to Manchester, my steam boat went from 2 to 3 miles per hour, and in returning, from 3 to 4 miles; and I am confident might be propelled from 4 to 5 miles per hour, without causing so great a wave as another boat going half a mile slower.

This would be a rate quite sufficient to induce passengers to adopt that mode of conveyance, especially to mechanics and their families, going from one manufacturing town to another. But it would soon be not alone the industrious and saving portion of the community, who would travel by the canals, because these pass through beautiful parts of the country where no roads do, and would, therefore, be adopted by parties of pleasure in the summer, if canal steam boats were once properly fitted up for passengers, and at all times by invalids, and those that were not in a hurry.

I estimate the saving of expense as follows:-A ten horse steam engine, placed in one long narrow boat, and occupying, with the other machinery, not one-third of the measurement tonnage, carrying passengers and light goods, and towing another boat, at the rate of 4 miles per hour, would not consume more than 1 cwt. of coals per hour, which, where coals are cheap, which is usually the case on canals, would not be more than from one-third to one-eighth of the present cost. In all the wide canals, both boats could go into the locks together, and thus lose no time in passing them. In this manner the trade might be carried on from London to Coventry, or Atherstone, as in all that long distance, there are only three locks where the two boats could not pass together.

I am your most obedient servant,
DAVID GORDON.*

FRENCH PATENT.

Brevet d'Invention, to MM. BRACONNOT and SIMONIN, for the manufacture of a substance analogous to wax, called CEROMIMEME, proper for making Candles and Soap, and producing, in the process, Sulphate of Potash.

THIS Substance, which may be substituted in place of wax, for many purposes, but particularly for producing light, is extracted from all animal fats, by the following process:-

The fat, or suet, from which the concrete matter is desired to be extracted, is diluted with a variable quantity of volatile oil, commonly that of turpentine. The mixture, placed in cylindrical boxes, lined with felt, and whose sides and bottoms are pierced with numerous small holes, is submitted to a gradual and very strong pressure, which expresses the volatile oil mixed with it, and along with it the most fluid part of the fat employed; the solid substance remaining in the boxes, is then taken out, and boiled a long time with water, to remove the odour of the volatile oil. It is afterwards kept in fusion for some hours, along with animal charcoal, recently prepared, and then filtered while boiling hot, and left to cool. This substance is then of a brilliant white, semi-transparent, and brittle, and without taste or odour.

This substance, though very fit for producing light, cannot, however, be employed for that purpose in this state, on account of its too great fragility, which neither permits it to be moulded, or to be moved about; a sort of ductility and tenacity can be communicated to it by a slight contact with chlorine, or hydrochlorine (mu

The patent to which the above letter refers, was obtained as early as 1825. We have not by us the volume of the Repertory in which it appeared, but the letter gives a sufficient outline of the nature of the invention. The reason for inserting it, is, to exhibit the fact of the existence of such a plan, to those who have, recently, applied for patents from the United States, for a similar invention, as this has occurred in several instances.-EDITOR.

riatic acid;) a fifth part of bees' wax, mixed with it, produces the same effect. It is then readily applicable to use, and candles can be moulded from it, which are as agreeable in burning as those made with wax.

The oil expressed, or the more fluid part of the grease employed, containing, besides the volatile oil, which may be separated by distillation, a considerable quantity of the concrete matter, which it draws off and holds in solution, being purified and whitened by bone charcoal, is eminently fit for making excellent soap for the arts, and even for domestic use, its odour being weak, and not too disagreeable. This animal oil, first saponified by the potash of Vosges, is formed into a hard soap with a base of soda, by means of the sulphate of soda, which is of small value, and found abundantly in the saline waters of the departments.

This process has the advantage of affording to commerce sulphate of potash, sought for by manufacturers of alum.

ENGLISH PATENTS.

TO FRANCIS WESTBY, Cutler, for his invention of certain improved apparatus, to be used for the purpose of Whetting or Sharpening the Edges of the Blades of Knives, or other Cutting Instruments. Enrolled July, 1828.

An apparatus for sharpening edge tools, by means of two grooved steel cylinders, was the subject of a patent granted to J. Felton, in June, 1827. The invention now before us, is upon the same principle, but different in form. It consists of a box, containing several straight bars of steel, with file edges, which are fixed at acute angles, crossing each other; and the knife intended to be sharpened, being drawn to and fro with its edge downwards, touching the angles at which the steel bars meet, will become sharpened by the operation of filing.

The accompanying figure shows the apparatus in perspective; the dotted lines representing the parts within; a, a, is the box, or case, containing the steel bars b, b, b, which are placed alternately at opposite angles, crossing each other. These bars are held fast by the

screws c, c, which pass through the ends of the box, and bear up against the sides of the two outer bars, confining them all firmly in their places.

The edges of the steel bars are cut with fine grooves, extending lengthwise; and the knife introduced between the angles of the bars, being drawn to and fro, receives the operation of filing to a fine angular edge, which renders it thin and sharp.

In order to vary the angle of the steel bars, which will be sometimes necessary, according to the thickness of the knife, or other edge tool, required to be sharpened, the lower plate, or table d, on which these ends bear, must be raised or lowered. This may be done by turning the screws d, d, by which the moveable bottom, or plate e, is held up, and attached to the box.

As the file edges of the bars will wear away by use, they may be taken out of the box, and turned round, so that different edges may be presented at the angles, or their ends may be reversed.

Another contrivance of this kind for sharpening knives, has been invented by Messrs. Blake, of Sheffield. It consists of a series of these file edged bars, connected together merely by an axle passed through their centres, and may be set at any angle, and made fast by a screw. The contrivance is very simple, the cost but very trifling, and its use equally effective. EDITOR.

[Newton's Journal.

To LEMUEL WEllman Wright, Engineer, for an improvement or improvements in the construction of Wheel Carriages, and in the ` Machinery employed for Propelling, Drawing, or Moving Wheel Carriages. Dated April 15, 1828.

THE principal object of this patent, is the application of compressed air to work machinery, by which carriages may be propelled. The apparatus proposed for this purpose, is composed of two strong cylindrical cases, (apparently five or six feet long, and from twelve to sixteen inches broad,) with hemispherical terminations, for the reception of the compressed air, placed horizontally at the hinder part of the vehicle, below the level of the axle of the hind wheels; from which cases, pipes of communication pass to a third case of a similar form, fixed transversely behind them; from this, again, the compressed air passes through valves, to two cylinders, furnished with pistons like those of steam engines, and placed in a horizontal position; the piston rods of which act, by connecting rods, on cranks (at the opposite side of the same plane) formed on a horizontal axle, placed transversely, farther forward: from a wheel, or pulley, on which axle a band of leather, or of other proper materials, passes round another similar pulley, on the axle to which the hind wheels are fastened, and which, being made to revolve by the action of the cylinders, propel the carriage. The valves that admit