Defcription of a New Hydroflatic Prefs. 29 



A very full and c'lrcumftantial account of this procefs, which Mr. Defmond affirms he 

 received from a certain learned foreigner, was inferted in the Motnteur, and thence 

 tranflated and publifhed in the Englilh Courier fome time in the month of Auguft 1795. 



vir. 



Df-ription and AccrAint of a New Prefs operating by the Aclion of Water, on the Principle of the 

 Hydroflatic Paradox. Invented by JOSEPH BraMAH, Engineer. 



A^ I G. T, Plate II, is a front fe£lion of a common prefs for books and papers, and the like. 

 Fig. 2 exhibits a perfpeftive view of the fame inftrument on that fide to which the pump is 

 fixed. The letters diftinguifh the fame parts in both. ABCD is the frame. 1 is a flrong 

 metallic cylhider, in which the rammer or pifton EF moves. To the upper part of tliis 

 piUon is applied an iron table, by the motion of which upwards the preiTure is communi- 

 cated to the articles H. QR reprefents a fmall ciftern, containing water. Within this 

 ciftern is fixed a fmall forcing pump, of which K is the barrel, L the pifton, M a fide valve 

 formed of metal, and opening inwards beneath the pifton. The nature and effeiSl of this 

 valve may be eafily underftood from the figure. It confifts of a metallic rod, at one end of 

 which there is a nob turned conical next the ftem, fo as accurately to fit the conical face of 

 the hole into which it is put. The tail is filed on one fide, fo that it does not entirely fill 

 the cylindrical hole which it occupies; by which means a paftage is afforded for water 

 when the head of the valve is raifed. In the ftate of inaflion, the valve is kept fliut by the 

 operation of a fpira! fpring at the other end of the tail. N is another valve of the fame kind 

 opening downwards. O reprefents the rod of the pifton, with a contrivance for keeping a ver- 

 tical pofition during the working. The effeft of this contrivance will be underftood without 

 difficulty by comparing the two drawings. S is the lever or handle for working the engine. 



Its aftion is as follows: When the handle S is raifed, it brr.igs up the pifton L, which 

 would leave a vacuum beneath if the prcffiire of the atmofphere did not force the water in 

 through the fide valve M. The lever is then to be preffed down, which caufes the fide 

 valve to ftiut, and forces the water through the bottom valve N, whence it pafles through 

 the pipe P into the cavity F of the great cylinder I, and raifes the pifton or preffing rammer. 

 A repetition of the fame procefs forces more water in, and the preffiire may in this manner 

 be carried to a great extent. When it is propofed to relieve the adlion, the lever S muft be 

 preffed down, which, by the mechanical contaft of the lower extremity of the pifton L 

 againft the tail of the lower valve N, keeps that valve open. In this fituation, the lever TU 

 is to be preffed towards R, and will open the vaive M. Both valves being in this manner 

 opened at once, the paffage between the internal part of the great cylinder and the ciftern 

 QR becomes free, and confequently the table G and tlie rammer EF dcfcend by their own 

 weight, and reftore the engine to its original fituation. 



There is no difficulty in computing the force of this inftrument. If the diameter of tlic 

 barrel K be one quarter of an inch, and that of I one inch, that is to fay, four quarters of 

 an inch; one pound lodged upon the pifton-rod W will be in equilibrio with fixteen 

 pounds lodged upon the table G ; the weights of the parts of the engine attached to, and 

 moving with, each pifton, being refpeflivcly included. And if the length of the lever SY 

 be fifteen inches, and the diftancc XY between the centres of motion and of adion be 



6 two 



