CHAP, ii.] THE HYDRAULIC OR BRA 31 A ITS PRESS. 33 . 



CHAPTER II. 



THE HYDRAULIC OR BRAMAIl'S PRESS. AREOMETERS OR HYDROMETERS. 



ARTESIAN WELLS. 



I. THE HYDRAULIC PRESS. 



~r)ASCAL demonstrated that all pressure exercised at one part of the 

 -*- surface of a liquid is transmitted with equal energy in every 

 direction ; hence he inferred that with comparatively little effort a 

 considerable pressure might be produced, provided that a liquid, such 

 as water, be used to transmit the pressure, and also that the piston by 

 which the pressure is produced has a much smaller surface than that 

 of the piston which is acted on by the pressure. In a word, he proved 

 that pressure is transmitted and augmented in the proportion of the sur- 

 faces of the two pistons. Theoretically, this was the invention of the 

 hydraulic press ; but the difficulties of putting theory into practice 

 did not at once allow of its construction. For a long time it was 

 impossible to find any way of preventing the escape of water by the 

 joints of the piston ; an escape due to the very force with which the 

 liquid when only slightly compressed was forced against the interior 

 of the apparatus. A simple and efficient means of removing this 

 inconvenience was adopted in 1796 by an English engineer, Bramah. 



Fig. 14 represents the hydraulic press as used at the present day 

 in the industrial arts for pressing certain substances. These sub- 

 stances, c, are placed between two plates, one fixed to the upper part 

 of a solid structure, the other movable between uprights, and forced 

 upwards by means of the head of the largest piston P. This latter 

 descends into a cylinder full of water, M, which communicates by a 



D 



