Water is delivered from the pump A through a heavy lead pipe into the cylinder _B_ of the hydraulic press. The ram P is made tight by the leather packing _n_ and has a table or platform attached to its upper end as shown. The stationary part _Q_ consists of a heavy cast-iron plate supported by four wrought-iron or machinery steel columns. By operating the handle _M_ of the pump any substances placed between the table on the ram P and the plate Q may be compressed to any reasonable extent. The pressure which can be obtained by this press depends on the relation of the ram P to that of the plunger P. If the former has a transverse section fifty or a hundred times as large as the latter, the upward pressure on the ram will be fifty or a hundred times that exerted upon the pump plunger. By means of the lever M an additional advantage is obtained. If the distance from the fulcrum to the point where the power is applied is five times the distance from the fulcrum to the plunger P the pressure on it will be five times the power. Thus, if a man acts on M with a force of sixty pounds, the force transmitted by the plunger P will be 300 pounds, and the force which tends to raise the ram will be 3,000, supposing the section of ram is a hundred times that of the pump plunger. Over-pressure, is prevented by safety-valve shown in front of the pump A. Fig. 146 shows an enlarged section of the pump used in connection with this press. When the plunger _P_ rises a partial vacuum is formed below it and the suction valve _O_ rises allowing the pump barrel to fill with water through the strainer and suction pipe in the cistern. When the plunger descends the valve _O_ closes and the water passes through the discharge valve _h_ into the pipe _K_, thence into the cylinder _B_ of the press where it acts upon the ram. When the press has done its work the ram may be lowered by opening the relief valve _r_. The safety valve is shown at _i_. By removing the plug _h_ the discharge valve can be reached to grind it in when necessary.