344 



NOTE V. 



THE RESISTANCE MADE TO BODIES MOVING IN FLUIDS DE 

 DUCED FROM THE GENERAL PRINCIPLES OF DYNAMICS. 



1. The Equation of motion. 



a. The ordinary hydrodynamics. 



& How changed when &quot; internal friction &quot; is taken into account. 



2. The ordinary law of resistance. 



a. How deduced from the equations of motion. 



#. The general results of experiments made since Newton s time 



compared with the law. 

 7. The resistance should be deduced from a rigorous solution of the 



equations of motion adapted to the case under consideration, 



case of the pendulum. 



3. The resistance to a Pendulum. 



. Bessel s mode of expressing the resistance. 



$. The careful experiments of Sabine, Baily, Coulomb, &c. 



7. Poisson deduces the nature of the motion and the resistance from 



the ordinary Hydrodynamic equations. 

 5. On comparing the theory with experiment they are found not to 



agree. 



e. Professor Stokes takes into account the effects of internal friction. 

 The results agree with experiment, 



4. The resistance to Moating Bodies, 



a. The phenomenon of emersion. 



& Waves are excited in the Fluid. 



7. Strange variations of the resistance as the velocity changes. 



(1.) AFTER Newton the chief writers on Hydrodynamics 

 were the Bernoullis, Maclaurin, and D Alembert. The 

 equations which the latter obtained are the foundation of 

 modern Hydrodynamics. He had previously discovered 

 a general principle whereby every question concerning the 

 motion of bodies may be reduced to another corresponding 

 one concerning their equilibrium. Thus then the science 

 of Hydrodynamics may be reduced to that of Hydrostatics. 

 The simplest case to which we can apply this principle is 



