The Art of Weaving.

It is of importance to the manufacturers and mechanics of the empire, and cannot be wholly uninteresting even to mechanical philosophers, every where, that their attention should be drawn to a "Treatise on the Art of Weaving," which, we understand, will soon make its appearance, written by our ingenious townsman, Mr. Murphy. This gentleman is well known to the trade as one of the most scientific and intelligent weavers in this district, and his work is intended to afford a full explication of his art, embracing all its principles, as well as its multifarious and interesting details. It is written with much perspicuity, the different processes being at once concisely and clearly explained, and well illustrated by a series of engravings. At a future period we may be induced, by the importance of the subject, to give a more detailed account of this work; and we will then confirm our statements in its praise, by such extracts as our limits may admit of. At present we will only farther say, that it has been brought forward at the cost of much labour and expense; and that manufacturers in general will find it their interest not to remain unacquainted with it. The plates do credit to the graver of Mr. Maclure.

That the numerous Schools in Liverpool having created amongst the labouring classes of the community a commendable taste for useful reading, it is desirable to furnish Mechanics and Ap. prentices with the means of gratifying that taste, by offering them the use of a well-selected Library, subject to such conditions and regulations as shall, hereafter, be determined upon.

That the support and increase of this Library shall be effected by means of Benefactions and Annual Subscriptions, and by Donations of Books, and by such other means as may be deemed expedient; particular regard being paid by a Committee, to be appointed, to the exclusion of such Works as contain polemical divinity, or party politics.

That Benefactors of not less than £2 2s., Subscribers of not less than 4s., per annum, and Donors of Books amounting in value to £2 25, (to be test imaed by the Committee,) shall be Members of this Institution.

That those Mechanics and Apprentices who are not Members of this Institution, but who are de sirous of partaking of its benefits, shall, for the present, be furnished with Books, on being nominated thereto by such Members, and subject to the rules of the Institution.

That a Committee, now to be appointed, be empowered to draw up a Code of Laws for the government of the Institution, subject to the approbation of a General Meeting of the Members, on an early day.

Aberdeen Mechanics' Institution.

At a meeting of a number of manufacturers, master-mechanics, and other gentlemen in Aberdeen, R. Harvey, Esq. of Braco, in the chair, a committee was formed, for the purpose of founding a Mechanics' Institution. The committee advertised a meeting to be held on Tuesday last, which mechanics and others friendly to the Institution were invited to attend, when certain resolutions, respecting the proposed Institution, would be submitted to them.

On Two New Coloured Test Papers.

The following account of these test papers is abridged from the description given of them by M. C. Pagot des Charmes, who has used them for many years, with advantage, in testing for acids and alkalies.

The first is obtained from the violet pellicle, which covers the root of the small radish, (raphanus sativus oblongus;) the second from the skin of the common red radish, (raphanus vulgaris.) The directions with respect to the small radish are, to scrape off the coloured skin with a knife, and as it soon changes in the air, to collect them rapidly, put them in a piece of clean linen, and compress them, when a clear transparent blue fluid will be obtained. The test fluid may be preserved as it is, out of the contact of air, or made into a syrup, or laid on paper by a brush; and the paper thus prepared, preserves its fine sky-blue colour, in contact with the air, for any length of time. The test is extremely sensible to acids and alkalies.

The serapings of the common radish require to be bruised in a mortar before pressure; they do not yield so much choice, but the tint is very fine either in the fluid state, or on paper, and the test it affords is a very delicate one. preparations are recommended above litmus, by their being equally sensible, and yet unaltered in the air, and by being readily obtained every where.-Jour. des Phis. xcvi. 136.

These

New Vegetable Principle, Dalhine.

M. Payen has discovered a new substance in the bulbs of the Dalhia, which has been called "dalhine," and, besides it, an unchrystalizable sugar, aroma, a volatile, and a fixed oil, albumen, silica, and several calcareous salts.

To extract the dalhine, the pulp of the bulbs is to be diffused in its weight of water, filtered through cloth, the liquid mixed with one-twentieth its weight of common chalk, boiled for half an hour, and filtered. The residuum of the bulbs is then to be pressed, the solutions united and evaporated to threefourths of their volume; 4 per cent. of animal charcoal must then be added, and the whole clarified by the white of an egg. The liquor, filtered and evaporated until a film form on the surface, deposits dalhine on cooling. All the washings

are to be treated in the same way, and thus 4 per cent. of dalhine, will be obtained from the bulbs.

This substance, when pure, is white, inodorous, purverulent, tasteless, of a specific gravity 1.356, more soluble in hot, than cold water, not soluble in alcohol, but precipitated by it from aqueous solutions. Potash dissolves it, ammonia does not, sulphuric acid converts it into an unchrystalizable sugar more sweet than that of starch.

This substance has some analogy with starch, inuline, gelatine, &c., but differs from them in forming a granulated mass when its aqueous solution is evaporated, by its specific gravity and other qualities. Ann. de Chimie. xxiv. 209.

Pyrophorus from Tartrate of Lead.

Dr. Gobel, whilst working with the tartrate of lead, remarked, that, when heated in a glass tube, a very perfect and beautiful pyrophorous was produced.— When some of the dark-brown mass thus formed, was shaken out into the air, it immediately inflamed, and brilliant globules of lead covered the ignited surface; some of these changing, by degrees, into litharge, offered a very beautiful appearance. The ignition continues much longer than with other pyrophori, which circumstance, with the facility of preparation, make it a convenient means of obtaining fire.

The inflammation of these substances, as Dr. Gobel remarks, has been attributed, principally, to the presence of potassium, but this substance affords a new proof that other metallic compounds are susceptible of spontaneous inflammation on the accession of air.

Donations to the Museum of the Glasgow Mechanics' Institution.

From Mr. Thomas Duff-three Silver Coins and two Petrifactions.

From Mr. Peter Pattily-two Specimens of Copper Ore.

From Mr. George M'Lehose-brought from South Carolina, North America, a Rattle-snake Skin-a Wild Cat's Skin -a Tobacco Pipe, made by the Catawba Indians-three pieces of Stone, found near Columbia, made and used by the Indians for points to their arrows; and a small piece of Stone, of the kind they

MR. CROSS's new harness for superseding the use of draw-boys, being constructed on principles very different from any thing in common use among weavers, it is, as yet, but little understood by the few who have had the curiosity to inspect it, either from a desire to adopt such a great improvement, or from a wish to examine the mechanism of this ingenious machine. It will, therefore, we hope, be doing an essential service to the Trade, to attempt to give some explanation of the principles of its construction.

The inventor, far from being satisfied with the state of the old harness, applied himself, with much assiduity, to discover something fitted to the object he had in view. This object was to reduce the weight so much, that the weaver could, with ease, work the harness himself; and he thought if this grand object could be attained that the superseding of the use of draw-boys would not be a vain speculation. His research did not prove abortive; for he discovered a principle, the proper management of which relieves the operative of the weight, by making the machine counterpoise it. Hence it has been denominated THE COUNTERPOISE HARNESS MACHINE.

The engraving exhibits a geometrical elevation of the machine; and, consequently, all the parts of the frame-work and machinery must be considered as double, that is, having corresponding parts on each side of the internal system of knotcords, harness, and lashes.

AA, the carriage, or main frame that supports the whole machinery, which rests upon the cape of the loom, and is used instead of the box

and carriage, in the ordinary mode of harness-weaving. The carriage consists of two parallel pieces of wood, each 4 inches deep, 14 inches thick, and 9 feet long, firmly fas tened together by means of two cross pieces, a a, at the distance of about 1, or 2 feet from each other. BB, uprights, or parts of the frame mortised into the carriage; their dimensions, as well as those of the other parts of the machine, may be easily determined by constructing a scale from the length of the carriage, according to which they are all laid down in exact proportion.

C C, horizontal bars, of which the upper supports the suspension board, and the lower the neck, or directing board. b, the suspension board, for supporting the knotcords and harness; it is perforated with from 400 to 1000 small holes, according to the size of the machine, through which the lacing of the harness passes, and is fastened. c, the neck, or directing board, for guiding the harness, (instead of rollers,) also perforated with holes according to the tye or parts in the harness. dd, trap boards, for preparing the harness to make the figure, in which saw cuts, or saw draughts are made to admit the knotcords. k, the knotcords, by which the draught, or shed, is obtained for the figure. n, the suspension board, for the preparing knotcords, perforated with holes, according to the number of covers. oo, the trap boards, for preparing the lashes, in which are also saw cuts, to admit the preparing cords.

FF, the arms of the trap boards, to which the pushers are fastened, by means of small screws and nuts.