This apparatus is intended to supersede the cold rolling of plates in order to take the buckle out of them. The sheets are clamped in the jaws or grips shown, and the stretch is effected by means of a hydraulic ram connected directly to the nearest pair of jaws. The power is obtained by means of a pair of pumps run through spur-gearing by the belt pulleys shown. The action of the machine puts a strain on those parts of the plates which are not "bagged" or buckled, and this causes the surface to extend, the slack parts of the plate not being subject to the same stretching action. The machine shown is designed to operate on sheet iron from No. 7 to No. 30 gauge, and up to 36 in. wide, the limit for length being 120 in. About a dozen sheets can be operated on at once. The machine appears to have met with considerable success in America, and has been used for mild steel, iron, galvanized or tinned sheets, copper, brass, and zinc. The details of this machine are given in Figs. 1 to 8. Figs. 1 and 2 are a plan and side elevation of the bed of the machine, showing the position of the hydraulic ram. Fig. 3 shows the bars used for holding the back jaws in position, with the holes for adjusting to different lengths of the plates. Fig. 4 is a back view and section of the crosshead and one of the bolts that connect the moving grip with the hydraulic ram. Fig. 5 gives a plan and cross section of the back grip, and Fig. 6 is a back elevation of the same, with a front view and section of the gripping part. Fig. 7 shows the gear by which the jaws are opened and closed.
BRITTON'S PLATE STRAIGHTENING MACHINE.
THE SCHOLAR'S COMPASSES.
Among the numerous arrangements that have been devised for drawing circles in diagrams, sketches, etc., one of the simplest is doubtless that which is represented in the accompanying figure, and which is known in England as the "scholar's compasses." It consists of a socket into which slides a pencil by hard friction, and to which is hinged a tapering, pointed leg. This latter and the pencil are held at the proper distance apart by means of a slotted strip of metal and a binding screw. When the instrument is closed, as shown in the figure to the left, it takes up but little space, and may be easily carried in the pocket without the point tearing the clothing, as the binding screw holds the leg firmly against the pencil.
The mode of using the apparatus is so well shown in the figure to the right that it is unnecessary to enter into any explanation.—La Nature.
THE SCHOLAR'S COMPASSES.