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LIII. On the Principles of Pump-tVork, illustrated and ap- 

 plied in the Construction of a new Pump, tvithout Friction, 

 or Loss of Time, or If'^ater, in working ; humbly proposed 

 for the Service of the British Marine, ivith the Privilege 

 of His Majesty's Royal Letters Patent, By Benjam;!* 



MiiRTIN. 



[Continued fiom p. 1*9.] 



1. J. HE particles of fluids and solids are equally hard, solid, 

 and impenetrable. 



2. Fluid particles are affected by gravity, act upon each 

 other, and are subject to all the aftpptions and laws of mo- 

 tion in common with all heavy bodies. 



3. Their fluidity is owing principally, if not solely, to 

 their not being in contact with each other. 



4. For that reason the particles of fluids, a« such, can 

 produce no friction, or impediment to motion, among 

 themselves. 



Fig.l.* 



5. The weight of a perpendicular line of fluid particles, 

 as cd, is in proportion to the number of such particles, that 

 is, to the height cd. 



6. Therefore the preesure of the line cd on fi fixed point d, 

 in the bottom of the vessel ABCD, is proportioned to its 

 altitude cd. 



7. The pressure of the whole fluid upon the bottom of 

 the vessel, is therefore in proportion to the height of the 

 fluid and the area of the bottom of the vessel. 



8. From the nature of fluidity, a constant endeavour to- 

 wards an equilibrium, or state of rest, must obtain among 

 all the particles. 



9. But in case of an equilibrium of particles in a fluid, 

 each particle must have a central force ev»ry way equal. 



JO. Therefore fluids press every way equally. 



1 1 . Consequently, the lateral pressure of a fluid is equal 

 to its perpendicular pressure at the same depth. 



12. The lateral pressure against the line BD is just half 

 that upon the line CD in the bottom, if BD be equal to 

 CD. ^ 



13. The re-action of the particle d, as being fixed, is 

 equal to the pressure of the line cd, and must entirely sus- 

 tain it. 



14. But if a hole EF be made in the bottom of the ves- 



• See PLte V, given in our Number for November. 



T « «1, 



