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this, we take copper, drawn into wire of a proper size, and with a file form a pivot at the end of it, in size agreeing with the hole pierced through the watch-plate, and we rivet it by strokes with a hammer, and then cut it to a length sufficient to allow the dial to be placed at the distance of a line or more from the watch-plate. We then adjust the other feet in a similar manner, and lastly solder them with hard solder. We cut, with small shears, the dial around the watch-plate, laid underneath it in such a manner as to leave a small portion projecting beyond the watch-plate, and, with a round burnisher, raise a small border around the edge of the dial, on its convex side, in order to retain the enamel in its bounds. This done, we clean the plate from oxide, by leaving it in water slightly acidulated with nitric acid, until the copper is become bright all over. It must then be rubbed with a wire scratch-brush and water. This last operation disposes the pores in the copper to receive the enamel, and to retain it firmly after its fusion.

The enamel used for watch-dials is very white; and it is sold in the form of small loaves. In order to use it, these loaves are broken into morsels, and are then pounded in a mortar of hardened and tempered steel, but not so much as to reduce it into powder; it is sufficient to reduce it to the size of grains of sand, and as nearly as possible of an equal size. These are afterwards washed in a vessel of glass, with pure water, and stirred with a spatula, until the whole forms one white mixture; it is then left to settle, and the water is decanted. It is then repeatedly washed in several waters, until it becomes perfectly clean; they preserve those parts of the enamel which subside from the washing waters, in order to employ them for the counter-enamel, of which we shall speak presently.

When the enamel has been well washed, it is suffered to remain in the glass vessel, and they pour over it nitric acid, until it covers it to a trifling depth. They stir it from time to time with a glass spatula, and suffer the acid

to act upon it for twelve hours. This operation is intended to remove any metallic parts from the enamel which may have been detached from the mortar during the action of grinding, and which would discolour the enamel on fusing it.

At the end of the twelve hours the nitric acid is poured off, and the enamel is washed with common water, until it no longer contains any acid: lastly, it is covered with pure water, and preserved in that state for use.

They not only enamel the dials on their convex side, or that on which is to be painted in enamel the hours, &c.; but they likewise enamel the concave side, which they term counter-enamelling. The counter-enamel is necessary, to prevent the enamel on the face of the dial, when fused, aided by the action of the heat, from changing the curvature given to it. In order to avoid this inconvenience, both sides are covered with enamel, and fused at the same time.

They commence with the counter-enamel, and employ for this purpose the residue of the washings, as abovementioned; they place the dial-plate upon the broach, which is introduced into the hole in its centre, the concave side being uppermost. Then, after pouring off the water which floated above the counter-enamel deposited at the bottom of the vessel, they take it up with a steel spatula, and spread it equally all over the concave surface of the intended dial, so that it may cover all the copper. They then remove the broach, and apply a piece of fine linen to the enamel, which attracts and takes up the water in it. Without taking this precaution, on turning the dial, the counter-enamel would fall off.

To place the enamel on the convex surface of the dial, they replace the broach in the central hole, and charge the upper face of it with an equal layer of pure enamel, taking care that it well covers the borders of the dial, and the holes in it, so that the heat may not burn them. In order to remove the water which is contained in the enamel,

they place a linen cloth on the border of fhe dial; the linen attracts the humidity, and thus all the parts of the enamel are well arranged, and contained in the least possible space; they then strike with the handle of the broach slight blows, in order to level anew the enamel, and then again extract the water as before. This operation the enamellers term beating the enamel. Upon this being well performed, the beauty, and the polish, or glossiness of the dial depends; so that the enamel, when fused, may not contain ady cavities beneath its surface, but be perfectly united. In order to be certain that no water remains in the enamel, it is suffered to dry upon an iron plate, pierced full of holes, with three of its edges turned up, and laid upon live coals.

These preliminaries being fulfilled, the dial is placed in a reverberatory furnace, under a muffle, but it is very slowly introduced, in order to heat it gradually. It is suffered to remain at rest in the furnace, until the enamel is seen to commence entering into fusion; it is then gently turned round upon the iron plate, and again left at rest, in order that the heat, if unequal, may strike equally at one time or another upon all parts of the dial. When the enamel is melted, which is easily known by the polish upon its surface, it is withdrawn from the fire with care, and suffered to remain at the mouth of the furnace, in order that the enamel may lose its heat by insensible degrees; otherwise, in passing from a high temperature into a cold atmosphere, the enamel would crack and fly off.

After having thus passed the dial through a first fire, it is again placed in a weak nitric acid, and afterwards washed perfectly. The counter-enamel is then applied to those parts which remain uncovered, and a second layer of enamel, as white and pure as the first, is laid upon the face of the dial, with the same precautions as before. It is then again placed in the fire; and the operation is even repeated a third time, to give the surface of the dial its greatest beauty of polish.

If it should happen that the enamel contains any air-bubbles or blisters, these must be opened with the point of a graver, be filled with fine enamel, and the dial be again passed through the furnace; and this operation must be repeated until its surface is become uniformly polished.

The dial is now ready for painting. The hours, &c., are painted in a soft black enamel prepared on purpose, and which is called noir d'ecaille. This is ground very fine in an agate mortar, with a pestle formed of the same substance, and mixed with oil of spike lavender. It must be reduced to an impalpable powder; a day and a half is scarcely sufficient to grind a gros of it. We dilute this black for painting, with more oil of spike, and employ it to paint the hours, the divisions for the minutes, &c.

We would recommend that a mark be made on the edge of the dial, to indicate the place of number twelve, with a flle. The dial is then to be divided upon a platform, and the divisions be slightly traced from its centre with a black lead pencil, by the help of a division plate and its index; but previously, and with compasses, one point of which is furnished with a cone, and the other carries a port-crayon with a black lead pencil in it, we must trace the circular lines which contain within them the divisions of the hours, minutes, &c. When the painting is become perfectly dry, the dial must be fired for the last time in the manner above described, and with the same precautions.

II.-On the Arts of Painting and Working in Enamel*.

WITH A PLATE.

IN our last number we gave a description of the manner of preparing enamel colours. We have given in the preceding article the French manner of making enamelled watch-dials; and we shall divide the remaining methods of employing them into three distinct branches, viz. the art of painting in enamel, the method of using the clear *From the Dictionnaire Technologique.

and transparent enamels, and the method of working enamel by the flame of the lamp.

1. On the Art of Painting in Enamel.-We shall not attempt to give the history of the art of painting in enamel, as it may be found in several works treating on this subject. The art of enamelling upon earthenware is very ancient, but this is not the case with the method of painting in enamel upon metal, which cannot be traced beyond the reign of Francis the First.

Enamelling is performed either upon gold or copper. Some authors have indeed pretended, that there are painters of enamel upon silver, but we much doubt it. From the many attempts which we have ourselves made, we are convinced of the great difficulties which attend the practice. The silver is subject to swell, and cause blisters in the enamel, and thus form eyes, or holes in it. All our enamel painters employ gold and copper.

The goldsmiths prepare the plates for the painters in enamel. Their width and breadth vary according to the uses to which they are destined. The gold ought to be of twenty-two carats fine, or rather more; but if too fine it has not a proper consistence; and if not fine enough, it is liable to melt. They make an alloy, one-half of which they say is white, and the other half red; properly speaking, it is composed of one half silver, and one-half copper; the enamel which covers the metal is thus less liable to become tinged of a green colour, than when the alloy is made with copper alone.

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The workman forms around the edges of the plate a small ridge, or border. This ridge or border serves to retain the enamel, and prevent it from falling off, in applying it, by means of a spatula. The height of the border must agree with the intended thickness of the coat of enamel; but as this varies according to the nature of the work, so must the height of the border correspond therewith. We must however here remark, that when the plate is not intended to bear a counter-enamel, or a coat