ever the subject matter is unconnected with his interest or marital rights. The pinch of the case here, is, that the binding was to the husband. But in equity, and even in some instances at the common law, wherever a feme covert has power to act as if she were sole, she may treat directly with the husband. As, however, the matter depends on construction, it is urged that expediency requires that the act of assembly be so interpreted as to avoid the tendency to abuse of power, which must necessarily exist in every case like the present. That would be a grave consideration, were abuses of the sort not subject to redress. But an effectual corrective may be found in the supervising powers of the judges, who are bound to discharge wherever the contract is shown to be tainted with actual fraud or collusion, and in a case like the present, the transaction would be more strictly scanned than if the binding were to a stranger. We will not, however, discharge, of course, where, as in this case, the covenants appear to be reasonable and proper on the face of the indenture, especially where the application is not made till the apprentice has ceased to be a burthen. It is objected that the quantum of schooling is unreasonably small. It appears, however, from the apprentice's signature to the indenture, that he wrote a fair hand; and the great object of the binding being to learn the art and mystery of the master, I would hold an indenture valid, without any covenant for schooling at all, if it should appear that the education of the apprentice had been sufficiently attended to before. It, therefore, appears to a majority of the court, that no reason had yet been shown why the apprentice should not be remanded. Tod, justice, dissented.

FOR THE JOURNAL OF THE FRANKLIN INSTITUTE.

Description of a Machine for Grinding Painters' Colours, Printing Ink, &c. Invented by W. J. STONE, Engraver, Washington, D. C.

VARIOUS machines have been invented for the purpose of grinding colours, which, however, are applicable only in the large way. In my own business I have felt the want of one which would answer well as a substitute for the ordinary stone and mullar, and have constructed an apparatus for this purpose, which I have found to fulfil my expectations. The annexed drawing will serve to explain its structure. The principal frame is made of wood, properly braced together, and need not be described. A, is a round table, or slab of cast-iron, turned, and ground flat on its upper surface. This is supported by a shaft B, running upon a pivot below, and supported by a collar above, so that it may turn freely. To the cog wheel C, fixed upon this shaft, motion is given in any suitable way, as by another cog wheel geared into it, and turned by a crank, or a whorl upon the shaft, acted upon by a drum and strap. This cog wheel takes into a pinion, on the second shaft D, which has an arm E,

projecting from, and standing at a right angle with it. A cog wheel F, is firmly fixed by its centre, to a pin rising from the arm E. This cog wheel turns a pinion G, on the mullar H, which mullar is in two parts, the upper part, H, which serves as a weight, which may be increased or decreased at pleasure, and drops upon a square pin projecting from the lower, or grinding part. This pin is round, where it passes through the arm I, to admit the wheel F, to turn the pinion G, and consequently the mullar. The arm I, turns freely upon the pin projecting from E, and slides freely through a hole in the swivel K, the upper and lower part of which are connected by a pin and socket.

H

It is unnecessary to describe the action of the machine, as this must be evident from its construction. It will also be seen that the length of the arm E, must be proportioned to the diameter of the table A, that it may carry the mullar to the right distance from its edge, on either side.

W. J. S

SIR,-In a late visit to the city of New York, my attention was attracted to the church now being built in Canal street. Its front appeared to be a copy of that of the temple of Theseus at Athens. The ingenious arrangement of the bricks to produce the fluting of the columns, recalled to my memory the following contrivance used by the ancients to produce the same effect, and which I send you, with a hope that it may afford a useful hint to some of our architects.

In examining, several years ago, the ruins of Pompeii, I noticed several doric columns broken off a few feet from the ground, and this circumstance gave me an opportunity of observing their internal structure. I found they were composed of bricks of two different forms and sizes, as in the annexed diagram. The full lines show the form of the bricks, and the dotted lines show the joints of the course next below, and the manner in which these joints were broken so as to form a good bond.

The gradual diminution of the column was effected by making the lateral joints between the bricks larger at bottom. The central part was filled by a circular brick.

W. H.

On improvements in Marbling the edges of Books and Paper. [Translated from the Dictionnaire Technologique, for the Technological Repository.]

THIS art is confined to a few persons only, who take great pains to preserve it secret, and will not make any communications thereon, but under considerable remuneration. One of the most skilful workmen in Paris, to whom I had rendered some essential services, was, however, willing in return, to initiate me in his mysteries, and execute his processes before me; and he likewise furnished me with the necessary details, to enable me to describe them; not, however, without my engaging to conceal his name, lest it might draw upon him the animadversions of his fellow-workmen. The following is the process:

The utensils employed by the marbler are not very numerous:— First, a vat, formed of oaken planks, well fitted together, so as to be perfectly water-tight. Secondly, a small cylindrical staff. Thirdly, several earthen vessels, to contain the colours and other preparations. Fourthly, a small portable stove, or furnace. And fifthly, a grinding stone, of porphyry or marble, and a mullar, to grind the colours; these are indispensable requisites.

On the preparation of the gum.-Put into a proper vessel, half a pail full of water, or about eight or nine quarts, and dissolve in the cold, about three ounces and three-quarters of gum tragacanth, stirring it frequently for six days: this is termed the couch, or bed; and upon this bed are to be spread the colours which serve to form the marbling; they do not, however, mingle with each other. This quantity of gum is sufficient for marbling the edges of four hundred volumes.

A solution of gum, much stronger than the above, must likewise be provided, in order to increase the thickness of the bed, when

necessary; of which proof is to be made in the manner to be hereafter described.

Preparation of the ox-gall.-Put the gall into a dish, and add to it an equal weight of water, and beat the whole up well together; then add to it ten drams of camphor, which has previously been dissolved in one ounce of alcohol, and again beat up the whole thoroughly, and pass it through a filtering paper. This preparation should not be made earlier than the day before it is to be used, lest it should spoil by keeping.

Preparation of the wax.-Over a slow fire, and in a glazed earthen vessel, melt yellow virgin wax; when it is melted, it is withdrawn from over the fire; and then mix with it, by degrees, and stirring it continually, a sufficient quantity of essence of turpentine, to give it the consistence of honey. Ascertain when it has attained the proper degree of fluidity, by putting a drop of the mixture upon the nail, from time to time, and let it cool; and add more of the turpentine if it is too thick.

Like the ox-gall, the wax must not be prepared too long before using it.

Of the colours.-We do not employ the heavy mineral colours in marbling; animal and vegetable colours, and the ochres, are the only ones which can be employed with success. The other mineral colours are too heavy, and could not be supported upon the surface of the gummed water.

For yellow, we employ Naples yellow, or the yellow lake from weld. The golden yellow is made with terra de Sienna, in its unburnt state.

For blues, of different shades of strength, use the best indigo, known by the name of "the flower of indigo."

For red, either employ carmine, or carmine lake.

For brown, umber.

For black, ivory black.

The white is produced by the gall itself.

Green is produced by the mixture of blue and yellow.

Violet, by yellow and red.

And aurora, as in ordinary paintings.

The terra de Sienna, the flower of indigo, and the carmine lake, are employed separately, in the manner we shall describe, and make very fine and sharp figures, which may be varied to infinity.

On the preparation of the colours.-These are to be ground very fine, and made into mixtures, of the consistence of a thick soup, or bouillie, either upon the slab of porphyry, or one of marble, with the prepared wax and water, together with a few drops of alcohol. When they are well ground together, take up a small quantity of the colour with a palet-knife, which is inclined, to let the colour fall upon the surface of the gummed water, to prove its consistency. When each colour is ground and mixed up, it must be put into a pot, and kept apart from the others.

On the preparation of the marbling vat.-From the vessel which holds the prepared gum, take a sufficient quantity of it to cover the

bottom of the marbling vat, to the depth of an inch at least. Then add seven ounces of alum, in fine powder, and beat it well up, to dissolve the alum. Put a spoonful or two of this prepared water into a conical confectionary pot, in order to make the necessary trials with it, to ascertain whether the gummed water be of the proper consistence for use, as follows:

Take a little of the colour which has been ground of a sufficient consistence with the prepared ox-gall, and throw a drop of it upon the gummed water in the conical pot, and stir it in a circular manner with the small rod. If it extend well, and form a spiral figure, without dissolving in the gum, it is sufficiently strong; if, on the contrary, the colour will not turn, the gummed water is too thick, and water must be added to it, and be well mixed with it, by beating it up; but if the colour spread too much, and dissolve in the gummed water, then some of the stronger prepared gum water must be added to it, which was kept in reserve for this purpose. At every time of adding either water or gum, the whole must be well beaten up to make the mixture perfect. After every trial, the conical vessel must be emptied, and its contents thrown aside, and a fresh portion of the gummed water employed. When the gummed water has thus been brought to the desired consistence, it must be passed through a sieve into the marbling vat, to the height of an inch, as we have before said.

The marbling vat being thus prepared, and all the colours ground and thickened with the prepared wax, and ox-gall, so that they be not either of too thick, nor of too thin, a consistence, first take the gall, and spread more or less of it upon the gummed water. The colour first thrown on is to be less thick than the succeeding one, and that again thicker than the first, and so on. We first throw on the red for instance. All the other colours intended to be used are then thrown on, one after the other; that which is laid on second, presses the first on all sides; and as the number of the colours is the more considerable, so the first is spread, and occupies a larger space. When all the colours which we would employ are thrown on, if we desire that the marbling should take the form of a volute or spiral, we hold the rod upright, and then carry it along amongst the colours in a spiral manner. The colours are thrown on with a kind of pencil made by the marblers, thus:-They take for the handles the twigs of osier, about a foot long, and two lines in thickness; they also employ about a hundred hog's bristles for each pencil, and of the greatest length possible; they arrange these bristles all around the smaller end of the twig, and tie them strongly with packthread. These pencils, with their long bristles, more resemble brooms than pencils. With the assistance of these pencils, they throw on, here and there, all over the gummed water, the first colour; then, in the middle of that, the second; then the third, &c.; so that when they are spread, these sets of colours approach one another; they then stir them in a spiral or other shape, as they judge necessary. We shall give an example:

Suppose we would give the marbling the form known by that of