116 OF FLUID PRESSURE USED AS A MECHANICAL POWER. 



COROL. 1. If the tube, instead of being fixed perpendicularly to the 

 top of the vessel, were inserted obliquely into any part of its sides and 

 inclined upwards, the principle above exemplified would still obtain ; 

 and the pressure in the narrow tube may be produced, not merely by 

 the addition of a little fluid, but by the application of any kind of 

 force, such as the working of a piston and the like. 



2. If the bottom, or the cover of the cylindric vessel be made move- 

 able, the pressure on either may be brought to bear on any one point 

 of an external body, and may then produce an inconceivable com- 

 pression, as is very successfully done in the Hydrostatic Press, an 

 instrument, which, on account of the simplicity of its application, its 

 expeditious performance, and the almost unlimited extent of its power, 

 is altogether without a parallel in the annals of mechanical invention, 

 and the numerous purposes to which it is applied, entitle it to no 

 small share of popular approbation. 



This machine is not only used for pressing bodies together, with a 

 view of diminishing their bulk, in order to render them the more easily 

 stowable ; but it is equally applicable to the operation of drawing and 

 lifting great loads, and overcoming immense resistances, however 

 opposed to its action ; even piles, which have been driven to a great 

 depth for the purpose of forming coffer-dams, can be drawn by it with 

 the greatest facility, and moreover, trees of the greatest size and most 

 tenacious growth, offer but a feeble resistance to its energy ; and in 

 addition, iron bolts and cables, capable of holding the largest ships in 

 the British navy, are totally incompetent to resist its influence. 



An instrument possessing such immense power in combination with 

 so many other advantages, such as cheapness of construction, porta- 

 bility, and simplicity of application, certainly merits the greatest 

 attention, and too many attempts cannot be made to simplify the 

 theory, and render its operations easily understood ; we shall there- 

 fore, in the following pages, endeavour to unfold the principles, and 

 to describe its construction and mode of operation. 



