in the observed time by a body falling freely, multiplied by the ratio of the length to the base, of the plane. If we apply this formula to the observation on the Raritan, we shall have h1,715.633,12-h2-15.277,g'=' This last result represents very nearly the average for the whole length of Mr. Saxton's tape; the distance being 48.8, and the time 8 seconds. R 1 The value of g" is, therefore, 1.43, and = If we extend our calculation still further, and take the last measurement given by Mr. Luken's tape, we shall find the mean resistance to the ship's motion to continue nearly uniform to that period, notwithstanding the immersion of nearly 100 feet of her length, to an average depth of almost 4 feet. R The value of g", for this period of 114 seconds, is 1.509, and; W 1 ་ being somewhat less than the earlier average, because it is 32.89' less effected by the very high coefficients given in the first of a second, which involved the friction of rest. Morin's experiments upon the sliding of plane surfaces of wood upon wood, with coatings of tallow, give an average coefficient of seconds, occupied in sliding 59 feet, upon a slip of 3° 40′ slope, is 1° 55', the coefficient of friction, or natural tangent, of that angle being .0336, or nearly 1-30th. The angle of friction of the Princeton steamer, computed by the same formula, from a time of 54 seconds, occupied in sliding 19.62 feet, upon a slip of 4° 25′ slope, is 1° 53′, the coefficient of friction, or natural tangent, of that angle being .0328, or rather more than 1-30th. The mean of these two results, gives an angle of friction, for launching such vessels as these, of 1° 54', or a coefficient of friction of very nearly 1-30th. and when the surfaces moved from rest of * 1 The greatest value of the coefficient of friction found by the com 1 mittee, is ; the average of the two experiments, upon the Raritan 15.2 "and Princeton is 1 29.8 All the errors, if any exist, in the experiments of the committee, would tend to make the coefficient appear greater than it really is, and yet it is less than one-half the average determined by the experiments of Morin. The thickness of the coating of grease, in these cases, was more than one-fourth of an inch; and the great pressure must have rendered it liquid as the vessel passed over it-the heat generated being so great as to produce much smoking of the tallow, near the end of the launch. On Thomas Shriver's Bow-Spring for Carriages. The Committee on Science and the Arts, constituted by the Franklin Institute, of the State of Pennsylvania for the Promotion of the Mechanic Arts, to whom was referred for examination the Bow-Spring for Carriages, invented by Thomas Shriver, of Cumberland, Maryland, REPORT: That they have examined two carriages constructed upon Mr. Shriver's plan, which may be described as follows, having reference In a note appended to his table of friction, given in the "Aide Memoire," page 309, Morin remarks, that when the unguent is continually renewed, and uniformly distributed, this ratio can be reduced to 1-20th. In a table published in the same work, on page 307, he states the friction of rest, between woods having unguents of tallow, at 1-10th. to a drawing hereto attached. The running gears, or frame, which supports the carriage body, mainly consists of three longitudinal pieces, or bows, of wood, a, a, a, framed to the bolster, n, which is attached to the hindermost axletree, and to two transom pieces, or bolsters, m and k, fixed over the front axletree-the piece, m, being under the pieces a, and resting on the pivot of the front axle-and the piece k, being on the pieces a, and extending upon each side about six inches beyond them. Upon the ends of the transom-piece k, and upon the bolster of the hindmost axle, posts, f, are framed, which are connected to the ends of the two cross pieces, c and b, by iron rods, d ; the cross pieces, c and b, being framed and secured to the ends of the bow pieces, a, at a suitable bevel, to resist the tension strain of the rods, d. The upper ends of the posts, f, the rods, d, and the links, e, VOL. VII, 3RD SERIES. No. 2,-FEBRUARY, 1844. 10 are connected by bolts to the leather straps, o, and springs, g, which are attached to, and support, the carriage body. In light carriages, the front piece, b, is curved, as represented in the drawing, but in heavy vehicles, or stage coaches, it is usually made straight. The whole carriage frame operates as a spring, when pressed by the weight and action of the carriage body. The points, e, e, are drawn towards the centre, and cause the posts, f, to act upon each of the axles as a fulcrum, bending the bows, a, downwards in the centre, and upwards at the ends, by the tension of the rods, d. The committee, after a minute examination of the subject, feel justified in expressing a very favorable opinion of these springs, combining, as they certainly do in a high degree, the essential qualities of lightness, simplicity, cheapness, and durability. This opinion is sustained by the written testimony of some who have extensively used them, and by the experience of several members of the committee, who have ridden in, and examined, both heavy stage coaches, and light carriages, equipped with bow-springs, all of which are successful, and received their decided approbation. In the drawing attached, fig. 1, is a side elevation of the body of a light carriage constructed with these springs; and fig. 2, a horizontal projection, or plan. By order of the Committee, WILLIAM HAMILTON, Actuary. Philadelphia, December 14th, 1843. On Calderhead's Carpet Loom. The Committee on Science and the Arts, constituted by the Franklin Institute of the State of Pennsylvania, for the Promotion of the Mechanic Arts, to whom was referred for examination the question of the novelty of the Loom devised by Alexander Calderhead, for weaving carpets, REPORT:: That the main features of this invention, are placing the pattern cylinder under the warp, and causing it to act upon perpendicular needles, each of which has an eye through which a thread of the warp is passed, thus enabling each particular thread to be lifted hy the pattern, at the proper moment, to produce a shed for the weft to pass through, and form a point in the figure of the fabric in hand. The committee have not the slightest doubt, that Alexander Calderhead actually invented the improved loom before them, and think he deserves the highest credit for the ingenuity and perseverance with which, through many discouragements, he has labored to bring his loom to its present state of simplicity and perfection; and the committee will here incidentally observe, that they have good reason to believe that looms upon this simple plan will be found highly useful for weaving carpets, and similar fabrics of a coarse texture. Nevertheless, an examination of previous patents has brought the committee to the conclusion, that the same form of loom, in all its essentials, has been before devised, and made the subject of a patent, by C. M. H. Molinard, which passed the Great Seal of England on the 9th of April, 1833, (see Newton's London Journal of Arts, &c., vol. xv. conjoined series, page 287,) where the following description will be found: "The present invention is to place the roller which carries the pierced cards under the warp threads, in the back part of the loom, and to cause the pierced cards as they successively come into operation, to act against the under parts of a series of perpendicular needles, through the eyes of which the warp threads are severally passed." This description precisely applies to the loom before us, which, therefore, cannot be regarded as a new invention. By order of the Committee, Philadelphia, April 13th, 1843. WILLIAM HAMILTON, Actuary. On Laubach's Blacksmith's Tuyere Iron. The Committee on Science and the Arts constituted by the Franklin Institute of the State of Pennsylvania, for the Promotion of the Mechanic Arts, to whom was referred for examination a Patent Tuyere Iron for smiths' forges, invented by Joseph Laubach, of Middletown, Dauphin county, Pennsylvania, REPORT: That they have examined the model of Laubach's Patent Tuyere Iron, with a revolving, or vibrating, hearth. The improvement consists of a vertical cast-iron cylinder, about 8 or 10 inches in length, and from 4 to 5 inches in diameter, with a concave flanch at the upper end, that corresponds with and forms the bottom of the hearth; this flanch also projects inward, and contracts the opening in the cylinder to about 2 inches diameter; this aperture is regulated by a sort of triangular valve of cast-iron fixed on a rod that passes out in front of the forge, (similar to a throttle valve,) this valve regulates the quantity of blast, and closes the aperture when required, to prevent the small coal, or cinder, from falling into the cylinder, which is provided with a sliding bottom that may be withdrawn when necessary to discharge the coal, or cinder, that may have accumulated in the cylinder. There is a horizontal tube projecting from the side of the cylinder to receive the pipe of the bellows. We believe the arrangement is new. The claim set forth by the inventor, is for constructing the blacksmith's forge with a revolving, or vibratory, hearth; and in combination therewith, the cylinder with a basined rim, forming part of the hearth, and having a tube to receive the nozzle of the bellows: said cylinder receiving the blast from the bellows, and serving as a receiver for the small cinder, as before described. The committee are of opinion that it is superior to any of the former tuyeres that have been brought forward; they are, moreover, strengthened in their opinion by many certificates, which have been given of its superiority by persons who have made a trial of it, and would, therefore, recommend it to the notice of the public. By order of the Committee, Philadelphia, October 12th, 1843. WILLIAM HAMILTON, Actuary. |