Improved Refrigerator. BY MR. JACOB WILKINS, HAYLE. A model and drawing of this refrigerator was shewn to the judges at the exhibition, as applied to rapidly reduce the temperature of the wort in the process of brewing. The pipes for conveying the cold water were small and of thin tinned copper, and were fixed to a wooden frame, hinged to one side of the cooler, or "back," in order that they may be raised for the convenience of cleaning the latter, or for repairs. To ensure the exposure of every part of the cooling surface to the wort, the latter is made to flow in a contrary and zig-zag direction along the cooler, by means of cross divisions, which are alternately close at one end, and open at the other. These are also attached to the frames which carry the pipes so as to be lifted out together. An additional horizontal branch pipe is attached to the refrigerator for the purpose of emptying it before it is lifted from the cooler. By this arrangement the cold water which has been heated by the first of the wort is successively brought in contact with hotter and hotter portions of it. Improved Lock for Sliding Pannels and Doors. THIS lock is chiefly intended to be used on board ship, where sliding pannels and doors are in constant requisition. The projecting part of the bolt is in the form of the letter T, the head of the T being vertical, and entering a vertical and narrow opening in a plate let into the edge of the pannel. The bolt itself is cylindrical, and can be turned on its axis, so that the T head can assume the horizontal position, when it forms a sort of button, and allows the pannels and doors to be slidden along without separating them. The key is only turned once round. The first part of the turn raises a tumbler and delivers the bolt; on further turning it, it raises another tumbler, and draws forward a flat bolt at right angles to the first, and wholly concealed in the lock. This flat bolt carries three teeth which fit into corresponding cavities in the cylindrical bolt, and as it moves forward turns the cylindrical bolt one-fourth round, when the tumbler again falls and retains it in this position. The entire arrangement of the lock is very simple and effective, with extremely little liability to get out of order. Р Description of an Instrument for copying, enlarging, or reducing Drawings, and laying off a Ship's course. BY MR. STEPHEN TREWEEKE, HALSE TOWN. It consists of a protractor, with a blade attached, on which are engraven scales of equal parts, the centre of the protractor being the zero of the scales; the scales graduated on the arm or blade being in the same proportion to each other as the scale of the original plan and that of the enlarged or reduced copy. The instrument accompanying this description is constructed for enlarging to twice, or diminishing to one half, the scale. Figs. 1 and 2 represent the instrument as enlarging to twice the scale. Original Plan. Fig. 2. Enlarged Plan. Fig. 1 B To use the instrument, draw a faint pencil-line, A, B (figs. 1 and 2), on the plan to be copied, near the extremity of the work, and a corresponding faint line, A, B, on the intended enlarged plan; fix on some point, C, as a centre in each of these lines, into which central points insert two fine needles, against which, when in use, the dent or notch at the centre of the instrument must be brought to bear, which materially assists the operation, the instrument by Direct the blade towards some point, D, on the plan, and notice the angle the protractor makes with the line, A, B, and read off, by means of the lesser scale, the distance, C, D. Now remove the instrument to the enlarged plan, and fix it to the same angle as it made on the original, mark off, by means of the greater scale, the distance, C, D, and this point, D, represents the point, D, on the smaller plan. On large plans, where the instrument cannot command the whole from one central point, a new line, D, E, must be drawn through any two points, D, E, on the original, and another line through the corresponding points, D, E, on the enlarged copy, in which lines take new centres and proceed as before. In this manner the whole detail of the plan, however minute, may easily be transferred to the enlarged drawing with the greatest accuracy. It will be found advisable, in using the instrument, to read off the angle first, to avoid any chance of error in substituting the angle for the distance, or vice versâ. this means being more readily fixed. The advantages derived from the use of this instrument are― that it dispenses with the use of transparent paper, cloth, &c., the copy being made on the sheet on which it is intended to be finished, consequently it saves the labour of tracing and retracing, and, excepting the pencil, no other instrument is required. It may also be advantageously employed for all bearing and distance purposes, such as a ship's course, or a course of mine dialling, &c., all that is required being to fix the instrument to the required angle with the north and south, or east and west, line, and mark off the distance by the scale, which, in a course of mine dialling, gives the first draught taken; through this last point draw a line parallel to the north and south, or east and west, line, as may be required, and proceed as before, to any extent. In enlarging or reducing to any scale not generally used, such as 7 times 1-7th or 3-5ths the scale of the original, or in bringing plans drawn to customary measure into statute, a strip of paper may be gummed down on the blade of the instrument, on which scales may be constructed sufficiently correct for most purposes, one scale being made with black ink and the other with red, for the sake of distinction. Two instruments may still be more advantageously employed, one on each plan; on the blade of one should be engraven the scale of the original, and on that of the other the scale of the intended enlarged or reduced copy, or any two scales in the same proportion, a needle being inserted in a hole in the centre of each instrument, around which they may freely move without the necessity of being removed for each reading. Tale Water Gauge for Steam Boiler. BY MR. JAMES GOODFELLOW, H.M. Dock YARD, MR. GOODFELLOW having proved by experiment that thin plates of talc were capable of sustaining enormous pressure, and this material not being liable to fracture from changes of temperature, like glass, he has introduced it in the construction of gauges for steam boilers, as represented in the annexed cut. The talc, t, is secured to an oblong box by the perforated plates by means of several screws, and thus forms two windows through which the rise and fall of the boiler water-level may be easily seen. Two of these gauges were sent to the exhibition, the one here delineated is as the instrument is arranged by Mr. J. Anthony, |