APPLICABLE TO MATHEMATICS, &C, 339 



one point to another, to find the state of the 

 atmosphere at any other time. 



Intimately connected with the data of this 

 question is the science of Hydrodynamics, or 

 the motion of fluids. 



The theory of Hydrodynamics has been culti- 

 vated by most modern philosophers, since the time 

 that Newton gave his researches on the motion 

 of bodies in fluids resisting as the square of the 

 velocity. There is an able report on the recent 

 investigations in Hydrodynamics, by G. G 

 Stokes, M.A. published by the British Associ- 

 ation for the advancement of science. No one 

 can read with satisfaction the mathematical inves- 

 tigation of the general equation of fluid motion, 

 as given by Poisson in his Mecanique, and Moseley 

 in his work on Hydrodynamics, in consequence of 

 quantities being neglected in the course of the 

 process, whose ultimate influence, if carried on, 

 cannot be foreseen. After two such steps, as 

 neglecting quantities, Poisson arrives at an equa- 

 tion which he supposes to express the law of 

 continuity of the fluid, and which must vanish, 

 or be equal to nothing in the case of an in- 

 compressible fluid. There is no wonder why 



