All the tools are electrically driven. The plate-flattening rolls, which have 15 and 20 horse-power reversible motors, take plates 8 ft. wide, and the rolls are from 21-1/2 in. to 19 in. in diameter. The bending rolls are driven by a 20 horse-power motor. The plate-edge planers, shown to the left in the view, Plate XLII., facing page 96, are operated by 16 horse-power motors, and the plate is held on the table by means of hydraulic rams as well as screw-jacks. For drilling and countersinking plates there are several modern tools, each actuated by an independent electric motor. One of these is a three-standard drill, to deal with plates of the largest size. The spindles have a rise and fall of 10 in., and are fitted with self-acting, as well as hand, feed, and with the usual rack arrangement for the traverse of the head. Several radial countersinking machines, with 11-ft. jibs and spindles 2-1/2 in. in diameter, are driven by 10 horse-power motors. There are many heavy punching and shearing machines, nearly all of them having 42-in. gaps, so that they can punch holes at any part of the widest plates. As a rule, they are arranged to punch 1-1/2-in. holes through 1-1/2-in. plates at the rate of thirty holes per minute. The shears are of corresponding power. For dealing with angles and bars there are several interesting tools, in addition to shears and punches. Some of the shears cut 8-in. by 4-in. angles, and are driven by 10 horse-power motors. There are channel-angle shearing machines, taking work 16 in. by 6 in., and operated by hydraulic pressure. These machines are made with revolving gear to suit almost any angle of flange. There is also an hydraulic stamping press for bending angles and tees to form knee-bars and other stiffening pieces, the cylinders being 14 in. in diameter, working at a pressure of 800 lb. per square inch, with a stroke of 18 in. The machine, which has been constructed by Sir William Arrol and Company, Limited, consists of an hydraulic cylinder mounted horizontally on a massive table. On the ram-head there are former blocks, while on the table in front there are corresponding dies. The bar is placed on the table between the blocks and dies, and as these are forced together by hydraulic pressure, the bar between them is squeezed into the exact shape required. Not only is the operation expeditiously executed, but there is no uncertainty. The whole of the metal within the bar is retained inside the knee, which becomes thicker and broader, materially adding to its strength. As the moulds or dies can be made to suit any form, the machine can be utilised in the preparation of various details of structures, provided they are designed with a view to their production by aid of dies. The great economy resulting from the use of special machines is only realised when the designing staff remember that they must be kept employed.