10 HYDRODYNAMICS. 



circumstances of bodies floating on liquids, or sinking 

 or rising in them ; such as are now placed in the 

 elementary inquiries respecting specific gravity. The 

 second book comprises ten propositions, serving to 

 ascertain the different positions which would be assumed 

 by a parabolic conoid in a liquid; according to the differ- 

 ent relations of the axis to the parameter, and to those 

 of the specific gravities of the conoid and the liquid. 

 The strictness and elegance of the demonstrations accord 

 with the highest conceptions that can be formed of the 

 powers of that extraordinary philosopher; but they 

 relate to truths which now sometimes constitute the 

 amusements of school-boys. Contrast them for a moment 

 with the present state of hydrostatics and hydrody- 

 namics ; with the fine chain of researches which relate 

 to the equilibrium and pressure of liquids and elastic 

 fluids, whether simple or mixed, the stability of floating 

 bodies, their motions and oscillations when the equi- 

 librium is disturbed, the general principles which 

 determine the operation of liquids in motion, or of 

 liquids affected by solid bodies in motion, the operation 

 of pumps, the discharge of liquids through orifices in 

 the bottom or sides of vessels, the motion of water in 

 rivers, canals, open or closed pipes, the construction 

 of flood-gates, sluices, dams, and banks, the oscillatory 

 motion of liquids in syphons and other tubes, the per- 

 cussion and resistance of liquids, with their application 

 to the motion of water-wheels of different kinds, to the 

 structure and manoeuvre of vessels, and the entire prac- 

 tice of seamanship. How rich and diversified such 

 inquiries ; how vastly surpassing the discoveries of 

 Archimedes in hydrostatics, must be evident even from 

 this bare enumeration : but these, momentous as they 



