MECHANICS AND USEFUL ARTS. 39 



above, with cam-rollers thereon, to act upon the roller or rollers below, 

 one or two of which move up and down in their bearings, rising and 

 falling while revolving, to draw metal bars to any pattern, and of any 

 size, according to the pattern of the cam, and the speed of the rollers 

 and cam-shaft, which can be varied by gearing so as to make a small 

 cam roll a long bar, and vice versa. Scientific American, March 23. 



EXPERIMENTS WITH GALVANIZED WIRE AND HEMP ROPES. 



EXPERIMENTS have been made in Woolwich Dockyard to ascertain 

 the comparative strength of wire and hemp ropes. A w-ire rope, 3 

 inches round, and a hemp rope of 3 strands, ha\vser laid, common 

 make, 7 inches round, w r ere spliced together, and placed in the testing 

 machine, and, on the hydraulic power being applied, the hemp rope 

 broke in the middle on the strain reaching 11| tons, the wire rope re- 

 maining apparently as strong as when the experiment commenced. 

 A wire rope, 3 h inches round, was then spliced with an 8-inch hemp 

 shroud-rope, and, on the power being applied, the hemp rope broke in 

 the middle with a strain of I0h tons, the wire rope continuing appar- 

 ently uninjured. American Railroad Journal. 



MANUFACTURE OF IRON CASKS OR VESSELS. 



MR. S. DA COSTA has recently taken out a patent for "improve- 

 ments in vessels for holding solids or fluids, and in machinery for 

 manufacturing such vessels." The invention relates particularly to 

 the construction of barrel-shaped vessels of iron, in the manufacture of 

 which the patentee forms the body part by bending the plate or sheet- 

 iron, by means of rollers, somewhat similar to plate-bending rollers 

 used for boiler purposes ; the plate used being such as will form either 

 one half of the vessel, or complete the entire circle. The upper bend- 

 ing or shaping roller, for this purpose, is formed of a barrel-shape 

 (that is, larger at the centre than at the ends), more or less, according 

 to the shape to be given to the plate, while the under roller is the re- 

 verse of the upper, so as to receive it and squeeze the plate between 

 them. On the ends of the upper roller are two cutting disks, or edges, 

 which pare the edges of the plate, as it is passed between the rollers. 

 A third roller is employed to guide and give the direction to the plate 

 under operation, its position being variable so as to bend the plate 

 more or less as may be desired. The plate, after being heated red-hot, 

 is passed through the rollers, which, at one and the same operation, 

 bend, shape, and trim the body part of the vessel. 



The plate, after being bent, encircles the upper roller ; and in order 

 to remove it readily, the patentee forms one of the bearings of a spher- 

 ical shape, which allows the opposite end to be raised, for the purpose 

 of removing the bent plate. The rollers are so formed as to set back a 

 small portion of the plate at each end, so as to form an enlargement 

 for the reception of the ends of the cask ; the enlarged end is of a 

 cylindrical form, or rather slightly coned outwards, to render the 

 ends more easily introduced and fitted. The ends are formed of plate- 



