here used, as is already described, for dying straw, in the present Number. Yellow. After aluming the feathers, they are passed either through a bath of terra merita, or one of woad. From the three colours, red, blue, and yellow, we obtain the other compound colours, green, violet, lilac, and orange. By dyeing the feathers first yellow, and then blue, we obtain a green; the red, afterwards dyed blue, affords the violet or lilac; the yellow, afterwards dyed red, or rose colour, gives the orange. These shades may be varied according to the strength of the baths, or as we leave the feathers for a longer or a shorter time in them. Ponceau.—This is the most difficult colour to dye. We dye an orange in a bath formed of rocou (anatto), dissolved in an alcaline lye, and then pass the feathers many times through another, formed by boiling scarlet wool. We throw into the first rose-coloured bath the juice of citrons; into the second, brandy; into the third, alcohol at thirtyfour degrees; and add pure nitre to the fourth bath, and often to the fifth. This receipt, indeed, appears to us rather empirical; nevertheless we give it, as it is that which is mostly used by the plumassiers, although not by others. L. LIST OF PATENTS FOR NEW INVENTIONS, Which have passed the Great Seal since February 27, 1830. To John Braithwaite, and John Ericsson, of the New-road, in the county of Middlesex, engineers; for an improved method of manufacturing salt. Dated February 27, 1830.-To be specified in two months. To Enoch William Rudder, and Robert Martineau, of Birmingham, in the county of Warwick, cock-founders; for certain improvements in cocks, for drawing off liquids. Dated February 27, 1830.-In six months. To Charles Random, Baron de Berenger, of Target-cottage, Kentish-town, in the parish of St. Pancras, in the county of Mid dlesex; for certain improvements in fire-arms, and in certain other weapons of defence. Dated February 27, 1830.-In six months. To William Grisenthwaite, of Notting ham, esquire; for an improved method of facilitating the draught or propulsion, or both, of wheeled-carriages. Dated February 27, 1830.-In six months. To Henry Hirst, of Leeds, in the county of York, clothier; for certain improvements in manufacturing woollen cloth. February 27, 1830. In six months. Dated. To Moses Poole, of the patent office, Lincoln's-inn, gentleman; who in consequence of a communication made to him by a certain foreigner residing abroad, is in possession of a certain combination of, or improvements in springs, applicable to carriages and other purposes. Dated February 27, 1830.-In two months. To Joseph Chesseborough Dyer, of Manchester, in the county of Lancaster, patent card manufacturer; who in consequence of improvements made by himself, and communications made to him by a certain foreigner residing abroad, is in possession of certain improvements on and additions to machines or machinery, to be used and applied for conducting to, and winding upon spools, bobbins, or barrels, rovings of cotton, flax, wool, or other fibrous substances of the like nature. Dated February 27, 1830.-In six months. To William Griesenthwaite, of Nottingham, Esq.; for certain improvements in steam-engines. Dated February 27, 1830.-In six months. To Robert William Sievier, of Southampton-row, Russel-square, in the parish of St. George, Bloomsbury, in the county of Middlesex, sculptor; for certain improvements in the construction of rudders, and in navigating vessels. Dated February 27, 1830. -In six months. To Simon Thompson, of Great Yarmouth, in the county of Norfolk, mariner's compass maker; for certain improvements in piano fortes. Dated February 27, 1830.-In six months. To William Howard, of Rotherithe, in the county of Surry, iron manufacturer, one of the people called Quakers; for certain improvements in the construction of wheels for carriages. Dated February 27, 1830.-In six months. To Phillip Chelwell De la Garde, of the city of Exeter, gentleman; for certain improvements in apparatus, for fidding or un fidding masts, and in the masting and rigging of vessels. Dated February 27, 1830.-In six months. To Thomas Prosser, of the city of Worcester, Architect; for certain improvements in the construction of window sashes, and in the mode of hanging the same. Dated March 6, 1830.-In six months. To Thomas Richard Guppy, of the city of Bristol, sugar-refiner; for a new apparatus for granulating sugar. Dated March 6, 1830. -In six months. To Ralph Stevenson, of Coleridge, in the county of Stafford, potter; for improvements in machinery for making from clay, or other suitable materials, quarries, bricks, tiles, and other articles. Dated March 6, 1830.—In six months. To James Ramsay, and Andrew Ramsay, both of Greenoch, in North Britain, cordage and sail cloth manufacturers; and Matthew Orr, of Greenoch, aforesaid, sail-maker; for an improvement in the manufacture of canvas and sail cloth for the making of sails. Dated March 20, 1830.-In six months. To George Scott, of Water-lane, in the city of London, Engineer; for certain improvements on, or additions to windlasses, and relative machinery, applicable to naval purposes. Dated March 20, 1830. -In six months. To John Alexander Fulton, of Lawrence Poultney-lane, Cannonstreet, in the city of London, merchant; for an improvement in the preparation of Pepper, Dated March 20, 1830.-In six months. To William Erskine Cochrane, esquire, of Regent-street, in the county of Middlesex; for an improvement or improvements, on his patent cooking apparatus. Dated March 20, 1830.-In six months. To Benjamin Rotch, of Furnival's inn, in the county of Middlesex, barrister at law; for improved guards or protections for horses legs, and feet, under certain circumstances. Dated March 20, 1830.-In six months. GILL'S TECHNOLOGICAL & MICROSCOPIC* REPOSITORY. LVII.-On Improvements in Cutting Screws and ScrewNuts. By Mr. JAMES JONES, Engineer. WITH FIGURES. SIR, Well Street, Wellclose Square. I BEG leave to submit to the notice of the Society of Arts, &c., some alterations in the construction of dies and screwtaps, which materially diminish the labour requisite for tapping large screws and nuts. A. AIKIN, Esq. Sec. &c., &c. I am, Sir, &c. &c. J. JONES. The ordinary form of taps for producing the spiral groove or thread in screw-nuts, is that of a circle, of which four * We have now for upwards of two years made a point of inserting the valuable monthly communications on the microscope, and on entomology, by our friend Thomas Carpenter, Esq. and likewise devoted our plates chiefly to microscopic subjects, most of them indeed being drawn from the objects themselves, as viewed in his excellent microscope for opaque and transparent objects; fearing, that such another opportunity of enriching our work, with a series of new and original microscopic delineations might never again occur, and we now rejoice that we availed ourselves of the facilities he so kindly afforded us; as, from Mr. Carpenter's removal to a distance from the Metropolis, we shall lose the future opportunity of so conveniently doing so. It is indeed true, that Mr. William Tulley has obligingly offered us the use of his superior achromatic microscopes, but he resides at Islington, and can therefore only be occasionally resorted to, and, although, indeed, we always have our own Varley's and Adams's microscopes, and our own set of objects at hand; yet, the microscope can now be but a secondary object with us, instead of being, as latterly, a principally one; although we shall certainly occasionally devote a portion of our work, to articles on this highly interesting subject. + From vol. XLVII. of the Transactions of the Society for the Encourage ment of Arts, Manufactures, and Commerce. segments are filed off, leaving four smaller intermediate segments remaining; the parts corresponding to the chords of the different segments, forming very obtuse edges, by which the metal in the nut is squeezed or rubbed out. It is customary to use two taps,-a taper, or slightly conical one, with which the operation of tapping is commenced; and a plug, or cylindrical one, to equalise the hole, and make the thread perfect. The common tap requires to be worked into the hole in the nut, by an alternate advancing and receding motion ; its cutting being of so imperfect a kind, that the power requisite to urge the tap forwards, with a continually advancing motion, would be sufficient to wring the neck of the tap off, the resistance being greater than the strength of the steel can overcome. The altered form of the tap which I have adopted, with very satisfactory results, is a combination of both the taper and plug taps, the part next the point being conical, and the upper part cylindrical; and, to prevent the necessity of drawing the tap out of the nut, when it is tapped, the head of the tap is made less than the bottom of the thread, so that it drops through of its own accord. The tap is fluted, with four or more grooves formed along it, one side of each of which is in a line pointing to the centre; thus affording, in a cross-section of the tap, a form somewhat similar to that of a ratchet-wheel. About one-third of the threads have their tops filed down, to diminish the quantity of surface in contact, by which much labour is saved, as the greater part of the power requisite for tapping in the common way, is expended in overcoming the friction, and not in cutting away the superfluous metal in the nut. This answers perfectly well for nuts not exceeding one and threequarter inches in diameter; but for larger ones, as those of two or three inches, for instance, I have found it advisable to insert a cutter in the body of the tap, just at that part where the cone terminates; and by the action of which cutter, nearly the whole of the metal is cut out; the upper |