The expense of such machines is, it is admitted, rather heavy, but the subsequent advantages in point of economy are by no means inconsiderable; when it is considered, too, that this discipline has, by the reports already given of its effects, been salutary in diminishing the number of persons committed to prisons where it has been carried into effect, we cannot hesitate in recommending it.

As a corrective punishment the discipline of the stepping-mill has had the most salutary effects upon the prisoners, and will not be easily forgotten; while it by no means interferes with, nor lessens the value of, those prison regulations which provide for the moral and religious improvement of the criminal,

It may be added, that when the machinery of the mill has attained its proper speed, certain balls rise by their centrifugal force, so as to draw a box below the reach of a bell handle, which will then cease to ring a bell, placed in some convenient situation for the purpose, But, should the men at the wheels cease to keep up the requisite speed in the mill-work, the balls will descend, and a projecting pin on the box striking the handle, placed in the proper situation for that purpose, will con-* tinue to ring the bell till they go on again properly Thus, a certain check is kept on the labourers, and the governor or task-master apprized, even at a distance, that the full work is not performed.

The substance of this report is taken from a pamphlet published by the committee of the Society for improving Prison Discipline.

SMART'S Bow and String Rafter, and HOLDSWORTH's improved Method of constructing Roofs.

IN our report of Patents this month will be found Tomlinson's, for an improved Rafter for Roofs or Beams; and Gladstone's, for a Method of increasing the Strength of Timbers; to these it may be useful to add the two following Inventions.

Mr. Smart, of Westminster Bridge Road, having been long convinced of the great convenience of flat roofs in London, and other great towns, where space is valuable, considered that their principal objection arose from the necessity of very strong bearings, which were necessarily weighty and expensive. To obviate this he devised the Bow and String Rafter, which is constructed in the following manner:

Take a square spar of the usual size for a rafter, and by means of a circular saw make an incision in it as represented at b, b, Plate VIII. fig. 12. Then make a cut, c, at right angles in the middle of the rafter into the cut, b, and after that cut out two thin wedge pieces, d, d. This being done, raise up the pieces, a, a, to an angle of 10 or 12°, with the piece, b, b, and introduce the key wedge, e, of seasoned oak, forming a rafter, as shewn at fig. 13.

It is obvious that a weight pressing on the key wedge of this rafter (if the ends be properly supported) will be sustained till either the fibres of the wood forming the string are drawn asunder, or till the lateral cohesion of the wood forming the butt ends of the rafter is destroyed: at the same time, there is no lateral pressure on the wall, or other support. The Society of Arts gave Mr. Smart their silver medal for this invention. See vol. 37 of their Transactions.

Holdsworth's Method of constructing Roofs. 149

Mr. Holdsworth, of Dartmouth, constructed a roof of timbers which covered a building one hundred feet long by thirty-seven feet wide, in which a considerable saving of materials was effected, as well as a large clear space obtained in the roof, which afforded room for stowage, The mode adopted is represented in Plate VIII. fig. 14: a, a, are the side walls; b, one of the timbers of the uppermost floor resting on sleepers. Two pieces of wood, d, d, are put upon the top of the wall, resting also on sleepers. The principals, c, c, forming each pair of rafters, are then secured, at bottom, to the pieces, d, d, and are fastened to each other, at top, by iron pins. Each pair of principals are supported by two arched pieces, e, e; these pieces are in their grain, and bent on the plan proposed by Mr. Hookey, of Woolwich Dock Yard. They are cut lengthwise by a screw into three pieces to within one foot of the end, as at f, f. They are then placed in a steam kiln, and boiled until they bend freely; then attached to a bent mould, and left to cool to the required form; after which a few wooden pins are driven through to keep the pieces so cut from starting open.

These arched pieces, e, are to be let into the beams, b, and pinned to them: at their upper ends they cross each other, and butt against the opposite principal. They are also secured by iron straps to the short pieces, d, d, which are, hence, prevented from giving way or forcing out the wall: and the whole, thus put together, forms a stiff and complete framing, on which the longitudinal räfters, g, g, and transverse pieces, h, h, are fastened in the usual manner. In the middle of the building, where four principals and as many arched pieces meet, and consequently cannot cross each other, a sort of king-post is inserted, in which the ends meet, and are secured, as at fig. 15.

In the roof of a hay-loft or cottage, the same advantages may be obtained, by letting the principals rest upon short pieces of wood, which may, as before described, be attached by a strap of iron, to another piece going from the beam of the floor to the middle of the principal, immediately under the couple beam, where it may be secured. It may be made of straight timber; but in the country, where there is always crooked timber enough about a farm of no use for house work, this will be employed to greater advantage, as it will save what is of more value to the carpenter. The Society of Arts presented to Mr. Holdsworth their silver medal for this invention. See vol. 38 of their Transactions.

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Review of New Publications.

Bulletin de La Société d'Encouragement pour l'Industrie Nationale, tom. xix. Or, Bulletin of the Society for the Encouragement of National Industry. Vol. xix. quarto, pp. 380, with 16 plates; published with the approbation of the minister of the interior. Printed at Paris.

[We are indebted for the substance of the notice of this and the following work to the Revue Encyclopedique; as these notices contain information of importance to the arts, we are pleased in having an opportunity of laying them before our readers. We think, too, that some of our own associated bodies may profit by the hints here thrown out. They order some things in France, most certainly, better than we do in England.]

THE Society for the Encouragement of National Industry, animated with an indefatigable zeal, continues to carry the flambeau of truth into every branch of our manufactures. It is to its cares and sacrifices that

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Society for the Encouragement of National Industry. 151 we owe the prosperity of the industriel arts in France. It neglects nothing to excite in our artists a superiority over our neighbours which may dispense with our paying a tribute to foreigners for an infinity of objects, which we obtain at a great expense from their manufactures. A new machine, a new process, invented either in France or in any neighbouring nation, is no sooner made known to some member of the society than the council of administration causes it to be examined with care, and very often to be constructed or exemplified at the expense of the society, in order to be assured of the truth of the facts. As soon as its utility is acknowledged, the invention is inserted in the Bulletin of the Society, and made public by the press.

This valuable collection contains nothing but what has received the sanction of experience; and the reader may be assured of the exactness of the processes and of the goodness of the machines, of which it contains a description. It is, without contradiction, a most useful work for the intelligent manufacturer who is anxious to learn all which may interest him, and desirous of perfecting the manufacture in which he is engaged.

This collection has been for a long time justly esteemed, not only by the number of things which it contains, but also by the spirit with which it is edited, and the low price at which it is sold. The present volume is a quarto of 380 pages, with sixteen plates, three of which are four fold; two, three fold; six double, and five single; the whole being equal to thirty-five ordinary plates; and the price, nine francs, or seven shillings and ten-pence half-penny sterling; a novelty in book-making

* We have no English word corresponding to this: industriel arts, are those produced by industry.