The construction and operation of working parts of this punch will be easily understood by referring to the engraving, Fig. 142 where 18 represents the body or “punching bear,” 17 the ram, 19 the raising and lowering pinion to move the ram quickly to its work; 20 shows the die with punch in place above it, secured by its gland; 3 the punch head cistern, the screwed cover having a hole in its center to guide the end 2 of pump plunger 9, having cup leather packing 10, at its lower end; 5 represents the lower socket which carries the arm 4 to operate the piston 6. The suction valve 11 is supported by the spring underneath; 12 is the safety vent; 13 the release or lowering valve operated by the stem 7 which is pushed downward by the projection of the piston 6 whenever the lever is turned and pressed downwards as described in lowering the lifting jacks. The relief valve is kept seated by the spring 14. 8 represents the body of the pump 16 its packing and 15 the ram packing ring. No. 16 does not move, but the ram 17 does, having a cup leather reversed at its upper end applied in the same way and manner as 16, with screwed packing ring. The discharge valve is located behind the pump plunger 9 and is, therefore, invisible. _A hydraulic punch mounted upon three legs_ or supports is shown in Fig. 143, and it also has a shackle at its back to suspend the punch in mid air as occasion requires. [Illustration: FIG. 143.] The details of this punch are like Fig. 142. It has two guards, one each side of the punch to pull the material operated upon off the punch as it is raised by the lower lever. Another very convenient style of hydraulic punch is shown in Fig. 144 where A represents the body of punch, B the operating lever with the lowering or adjusting lever shown broken off. The punch proper is shown at C. The center of gravity of this punch has been so nicely located that by suspending from the handle the ram hangs plumb. [Illustration: FIG. 144.] [Illustration: FIG. 145.] THE HYDRAULIC PRESS. The hydraulic press consists of 1. A Lever, 2. A Pump, 3. and a Ram working in a 4. Cylinder. Bramah in the year 1796 brought out a very interesting apparatus which illustrates the law of the equality of pressure which has been widely adopted in the practical use of the hydraulic press. The principle upon which this press works is due to Pascal but it remained for Bramah to put it to practical use. Enormous pressures are developed by operating the hand lever shown at _M_ in Fig. 145, which is connected with pump plunger P. The pump barrel A is very thick and receives its supply from the cistern H through the suction pipe _a_. [Illustration: FIG. 146.]