TRUMAN'S PATENT FILTER. [Patent dated, February 10, 1845; Specification enrolled, August 10, 1845.] FILTERS are already so numerous, and of such variety, that one would have thought it next to impossible to invent anything of the kind having the least pretensions to novelty. Here, however, is one which is not only new, but of a highly philosophical and efficient character. In this filter, the pressure of water, the pressure of the atmosphere, and the force of capillary attraction, are all combined to produce the desired effect in a way which we do not remember to have seen before. First, a close hollow vessel of a porous quality, is set in the midst of a cistern of water, and the water left to find its way through it by its own pressure-which it does slowly, but very surely leaving on the outside of the vessel every impurity which may have been mechanically intermixed with it. As the water flows into this vessel, the air which it displaces is expelled through a vent pipe carried to the top of the cistern. Then, to draw off the filtered water, three several methods are employed; in the first, which depends on the pressure of the atmosphere alone, and is applicable only where the immersed filter is meant to be a permanent fixture, a pipe is carried from the filter through the side of the cistern, and opened and shut by an ordinary tap; in the second, which admits of the filter being moveable, a syphon acting by capillary attraction is made use of; and in the third, which is also suitable for moveable filters, a syphon is employed of the ordinary sort, only that it is provided with means for stopping the flow of the liquid when required. (1.) Figs. 1 and 2 represent the first of these arrangements. A is the close vessel, which is of a cylindrical shape, and which is made of some natural stone of a porous quality, such as the ordinary dripstone. B is the vent air pipe, which rises from the vessel A. CC is the tank or cistern containing the water to be purified; D, a standard, on which the close vessel A is mounted; E, the discharge pipe, which is carried from the close vessel A, through the side of the tank or cistern, and is opened or shut by the tap F. (2.) The capillary syphon is represented in fig. 3. The body of it consists of a number of small metallic tubes of about three-eighths of an inch in diameter, bound closely together. The short end of it is inserted through an orifice in the top of the filtering vessel A, which orifice is then made air-tight by soldering, or by any other suitable means. The air pipe D is curved like the syphon, and inserted into the filtering vessel through the same orifice. For the small metallic tubes a number of threads of cotton, or other fibrous substance, capable of acting by capillary attraction, may be substituted, taking care to enclose in a metallic tube, or other water-tight case, the portion of them which is exposed to the water in the tank outside of the filter A. (3.) The third arrangement is shown in figs. 4 and 5. G is a ball valve, attached to the short end of the syphon, which, on the water in the filtering vessel A falling below the line a a, closes the mouth at that end; and H, a cup affixed to the long end, with a tap to it, by the turning of which tap the filtered water is either drawn, or shut off. K is a funnel placed at the highest portion of the bend of the syphon, by means of which it may be charged previous to water being drawn off by the tap. Or the same thing may be accomplished, by opening the filtered water tap, and applying a blast from the mouth to the air-pipe D D, which is provided with a mouth-piece for that purpose. When it is desired that the filtration should be conducted very rapidly, an air-pump is attached to the vent air pipe D, as shown in fig. 5, by means of which the air is time after time exhausted, or nearly so, from the vessel A, and the percolation of the water through it thereby proportionally accelerated. A very clever arrangement for carrying water on the same system to considerable heights-as, for example, from the basement story of a house to the upper stories, or any of them-is shown in fig. 6. A is the filtering vessel and water reservoir as before. I is another close vessel placed in the upper story, which communicates at bottom by a vertical pipe b, having a self-acting valve at c, with the vessel A, and at top by a TRUMAN'S PATENT FILTER. 99 Fig. 6. pipe d, with an air-pump L. By working the pump the air becomes exhausted from both the vessels A and I, and the filtered water ascends into I. The cock e, being then opened to readmit the air to the top of I, the filtered water in that vessel may be drawn off from it by any of the cocks, f, g, or h; or by making use of a two-way tap, such as is represented in figs. 7 and 8, the water may be drawn off from I without opening the air-tape; this two-way tap being so constructed as to admit the ingress of the air through the upper orifice simultaneously with the outflow of the water through k. The upper vessel I, must of course be made sufficiently strong to withstand the external pressure to which it is intended to be subjected. Mr. Truman states, that though he has "directed that the filtering vessel A should be made of some natural porous stone, because he considers this substance to be under most circumstances the best suited for the purpose, he does not restrict himself to the use of that material, for there are various artificial substances or mediums which may be substituted for it, and in some cases with advantage, as where the natural porous stone can only be had from a great distance and at a heavy expense. The filter might, for example, be made of unglazed stoneware, or of a number of layers of cloth kept distended by strong hoops, or of two concentric metal vessels perforated all over with very minute holes, and having a space between them filled up with fine gravel and sand." GEOMETRICAL CONVERSION OF CONVEX (Continued from page 84.) cone. From the peculiar relation that subsists between the cone and cylinder, we may at once infer that a process somewhat similar to that followed in respect to the latter, will be required for the solution of the present problem; we shall therefore adopt a similar means to discover what the nature of the process is; and for this purpose, 100 Put d = == GEOMETRICAL CONVERSION OF CONVEX SURFACES. the diameter of the base of the h the altitude or height, some- andr to the radius of the circle whose superficies; Then, since the convex superficies is expressed by the rectangle under half the circumference of the base and the slant height or length of the side, the expression for the convex superficies is 3.1416 × ds; and as in the case of the cylinder, this expression and that for the area of the equivalent circle, are equal between themselves, by comparison we get 3.1416r2=3·1416xds, and casting out the common factor, 3'1416, it is r2 = ds; therefore, by converting the terms of this equation into an analogy, we obtain d:r::r:s; from which we infer, that the radius of the required circle is a mean proportional between the radius of the cone's base and its slant height; hence the following construction: Let A CD, fig. 2, be a right cone, the diameter of whose base is A B, vertical height or axis C D, and slant height or length of the side A C. Produce C A to Q, and make A Q equal to A D, the radius or semi-diameter of the base; then is C Q considered as one line equal to CA+AD, the sum of the slant height and the radius of the base. Bisect C Q Fig. 2. in P, and on the point P as a centre, and with P C or P Q as a radius, describe the semicircle Cm RnQ; then at the point A in C Qerect the perpendicular A ́S, intersecting the semicircle just named in the point R, and AR will be a mean proportional between the slant height C A and the semi-diameter A D; for by construction AQ is equal to A D. Draw the straight lines CR and Q R from C and Q; the extremities of the diameter CQ; then by the nature and conditions of the problem, the triangles QRA and R C A are similar; hence it follows, that AQ:AR:: AR: A C, so that AR is obviously a mean proportional between CA and A Q. But we have shown before that the radius of the equivalent circle is a mean proportional between the slant height AC and the semidiameter A D, and consequently, AR is the radius of the equivalent circle. Upon R as a centre, with the distance RA as a radius, describe the circle A m Sn; then will the circle so described be equal in area to the convex superficies of the right cone A C B. Since the diameter of the base A B and the vertical height or axis C D, are the data proposed in the problem, it will be necessary in case of a calculation being required, to determine the slant height or length of the side A C in terms of A D and CD; now CD A is a rightangled triangle, from which we get A C=√A D2+C D2; and by restoring the proper symbols, it becomes `s= }√d2+4h2; in which case we have 1 }d: r : : r : } √ď2 + 4 h2; or r2 = √ √ d2 + 4h3, an expression of the same value as that which we have previously obtained, but something more complicated in its form, as it involves the calculation of the slant height A C. What we have here said refers only to the case in which a calculation is required; but when the solution is to be strictly geometrical, the slant height is at once determined from the axis and diameter being given. If it were required to find a circle, of which the area should be equal to the convex surface of an oblique cone, the problem is one of very great difficulty, and could not be resolved by straight lines and circles, nor even by the application of lines of the second order. (To be continued.) ACCOUNT OF THE VARIOUS IMPROVEMENTS MADE IN THE STOCKING FRAME FROM ITS INVENTION TO THE PRESENT DAY, AND ITS CONNEXION WITH THE LACE MANUFACTURE. [From Report of the Commissioners appointed to enquire into the condition of the Framework Knitters, 1845.] In a memorial addressed to the Lords of the Treasury in 1834 against the exportation ACCOUNT OF IMPROVEMENTS MADE IN THE STOCKING FRAME, ETC. of machinery, from the merchants, manufacturers, and others at Nottingham, engaged in the manufacture of silk and cotton bobbinnet lace, the introduction and importance of this manufacture is thus spoken of : "The fabrication of thread and silk lace is a very ancient and extensive manufacture, the manner of making which by the hand is a very complicated, tedious, and slow process, and, of consequence, such lace is very expensive and costly. "That the manufacturers of such lace, particularly of the most costly fabrics, principally resided in the northern provinces of France, in Brabant, Flanders, and the Low Countries, where the female population were to a great extent employed in making lace. "That although the making of the inferior kinds of lace was extensively carried on in the counties of Buckingham, Bedford, and Northampton, and the superior fabrics to a small extent in Devonshire, yet such was the demand for foreign laces in these dominions, that Parliament was induced to prohibit the importation of such laces, as it caused a visible diminution in the amount of British specie, and weakened the resources of Britain, whilst it added to the power, wealth, and aggrandizement of France, and the possessors of the Low Countries. "That the superseding of hand labour by machinery, in the carding and shearing of cotton and other cloths, had been early invented in England, and the use of such carding machinery was prohibited (by the 5th and 6th of Edward VI., cap. 22), on account of its damaging the cloth in the process, from the imperfection of its construction; so that the knitting or stocking frame was the first invention successfully used for superseding hand labour by the use of a machine, in making clothing. "That in the latter end of the reign of His Majesty George II., or about 150 years after the invention of the said knitting machine, a number of appendages were applied to the said stocking frame, one of which, termed the tickler machine, by mere accident, was applied to the making fabrics in imitation of lace, by removing the stocking loops in various directions. This attempt was succeeded by another invention, termed a point-net machine, consisting of a machine appended to the frame, which made the net without removing the stitches; and this invention, after numerous attempts to make it sound, nearly superseded the making of silk lace by the hand. "Your memorialists further show that this net, though an imitation of bobbin-lace, was yet inferior in many essential points to those fabrics, particularly in retaining its appearance of lace, when unstiffened; not 101 withstanding which defect, no less than 1200 workmen were employed at one period in making it, and more than 20,000 persons in ornamenting the net, and preparing it for sale. "That so early as the year 1770 attempts were made to produce bobbin-nets by machinery, in exact imitation of those made by the hand, having the threads traversed and twisted round each other. To accomplish this object a machine was invented to plat a warp at both ends, in imitation of a machine brought from Switzerland, but this was found too slow a process; small brass winding bobbins, having teeth, and rolling in other rack teeth, were essayed; threads wound upon wire, tier upon tier of hooks, revolving wheels on slides, and hundreds of other experiments were tried, and though the bobbin mesh was by these means effected, yet the want of speed and accuracy of working rendered all the plans abortive. Nume rous attempts were made during this period in Scotland, London, and many parts of the kingdom, to make fishing-nets by machinery, which was for several years also essayed at Nottingham. A workman employed in making and inventing such machinery at length discovered, through accidentally seeing a child at play, the formation of the bobbin and carriage now used in the bobbinnet machine, which was first applied to the making of fishing-nets. Notwithstanding this discovery, none of the inventors could apply it to a machine to make bobbin net. So great was the difficulty, and such the number of abortive attempts, that the projectors were ranked amongst the enthusiasts who were seeking to obtain the perpetual motion. Two men, named Simpson and Green, actually died from a disease of the brain, brought on by unremitting and unrequited study. "At length, in 1809, a machine to make bobbin net was completed, which had passed through the hands of no less than six of the most ingenious and indefatigable mechanics then known, whose labours had been abortive, though they had passed their lives in similar attempts. "The machine thus accomplished, after 40 years' experiments, in different parts of the kingdom, was yet surprisingly complex and slow in its movements, having 24 motions to the series for twisting the mesh, and four motions for the pins to secure the twist from unravelling. "This complex machine, before the expiration of the patent, was simplified so as to require only 13 motions to complete the same mesh, and two to prevent the unravelment; two other improvements reduced the motions to 11, and two motions for prevent, |