OF THE HYDROSTATIC PRESS. 137 



Into the side or base of the cylinder F, the end of a small tube bbb 

 is inserted, and by this tube the water is conveyed or forced into the 

 cylinder; the other end of the tube is attached to the forcing pump, 

 as represented in the diagram ; but this will be more particularly 

 explained in another place. 



A A are two very strong upright bars, generally made of wrought iron, 

 and of any form whatever, corresponding to the notches in the sides of 

 the flat table E, which is fixed upon the end of the piston r>, and by 

 workmen, is usually denominated the ' Follower or ' Pressing Table.' 



B is the top of the frame into which the upright bars A A are fixed, 

 and cc is the bottom thereof, both of which are made of cast, in 

 preference to wrought iron, being both cheaper and more easily 

 moulded into the intended form. 



The bottom of the frame cc, is furnished with four projections or 

 lobes, with circular perforations, for the purpose of fastening it by iron 

 bolts to the massive blocks of wood, whose transverse sections are 

 indicated by the lighter shades at GG. The top B has two similar 

 perforations, through which are passed the upper extremities of the 

 vertical bars A A, and there made fast, by screwing down the cup-nuts 

 represented at a and a. 



Fiy. 2 represents the plan of the top, or as it is more frequently 

 termed, the head of the frame ; the lower side Fig. 2. 



or surface of which is made perfectly smooth, 

 in order to correspond with, and apply to the 

 upper surface of the pressing table E in^. 1 ; 

 this correspondence of surfaces becomes ne- 

 cessary on certain occasions, such as the copy- 

 ing of prints, taking fac-similes of letters and 



the like ; in all such cases, it is manifest, that smooth and coincident 

 surfaces are indispensable for the purpose of obtaining true impres- 

 sions. 



The figure before us represents the upper side of the block, where 

 it is evident, that the middle part B, (through whose rounded extremi- 

 ties a and a, the circular perforations are made for receiving the 

 upright bars or rods AA,^. 1), is considerably thicker than the parts 

 on each side of it ; this augmentation of thickness, is necessary to 

 resist the immense strain that comes upon it in that part ; for although 

 the pressure may be equally distributed throughout the entire surface, 

 yet it is obvious, that the mechanical resistance to fracture, must prin- 

 cipally arise from that part, which is subjected to the re-action of the 

 upright bars. 



