OF NATURAL PHILOSOPHY. 181 



(189.) The necessity of this appeal to experiment 

 in every thing relating to the motions of fluids on 

 the large scale has long been felt. Newton himself, 

 who laid the first foundations of hydrodynamical 

 science (so this branch of dynamics is called), dis- 

 tinctly perceived it, and set the example of laborious 

 and exact experiments on their resistance to motion, 

 and other particulars. Venturi, Bernoulli, and 

 many others, have applied the method of experiment 

 to the motions of fluids in pipes and canals ; and 

 recently the brothers Weber have published an ela- 

 borate and excellent experimental enquiry into the 

 phenomena of waves. One of the greatest and most 

 successful attempts, however, to bring an important, 

 and till then very obscure, branch of dynamical 

 enquiry back to the dominion of experiment, has 

 been made by Chladni and Savart in the case of 

 sound and vibratory motion in general ; and it is 

 greatly to be wished that the example may be fol- 

 lowed in many others hardly less abstruse and 

 impracticable when theoretically treated. In such 

 cases the inductive and deductive methods of en- 

 quiry may be said to go hand in hand, the one veri- 

 fying the conclusions deduced by the other ; and the 

 combination of experiment and theory, which may 

 thus be brought to bear in such cases, forms an en- 

 gine of discovery infinitely more powerful than either 

 taken separately. This state of any department of 

 science is perhaps of all others the most interesting, 

 and that which promises the most to research. 



(190.) It can hardly be expected that we 

 should terminate this division of our subject without 

 some mention of the " prerogatives of instances " 

 N 3 



