234 PLYMOUTH INSTITUTION. 



October 8th. — Mr. Owen^s Lecture on the Resistance 

 of Fluids. 



After alluding to the importance of this subject, in a maratime 

 country like England, in consequence of its immediate connexion 

 with those branches of science on which ship-building depends, 

 Mr. Owen proceeded to state some of the theories of resistance 

 which had been investigated by Sir Isaac Newton and other phi- 

 losophers, together with some of the results of theory. These 

 results were stated to be obtained by the application of that law 

 of resistance which makes it vary as the square of the velocity. 

 In certain velocities this law is not far from the truth. Some of 

 the difficulties and uncertainty of a theoretical consideration of 

 the subject, were pointed out, and the uniform avowal of philo- 

 sophers was stated as to the impossibility of successfully pro- 

 secuting it except by experiment. 



Some account was given of a very interesting set of experiments 

 by Sir Charles Knowles, with a view to ascertain the action of 

 a running stream of water against an obstacle at rest. He intro- 

 duced into this stream certain coloured filaments of a liquid 

 which would not mix with the water, and thus the paths of these 

 filaments were traced out. This was done with great care, and 

 it appeared that, whatever was the velocity, the curves described 

 by the filaments, when deflected from their course by the resist- 

 ance of the obstacle, was in all cases the same ; from which it 

 results, by the principles of mechanics, that the force which 

 keeps the filaments in this curve must vary as the square of the 

 velocity. This was an unexpected and most interesting result, 

 pointed out by the experiments of Sir Charles Knowles. 



Some allusion was made by the lecturer to the experiments 

 which were conducted on a large scale in France, at the expense 

 of the French Academy, by D* Alembert, Condorcet, aud Bossut; 

 but he dwelt at considerable length on some very valuable expe- 

 riments that were made, on the resistance of fluids, in England, 

 chiefly under the direction of the late talented Colonel Beaufoy, 

 in furtherance of the views of the Society for the Encouragement 

 of Naval Architecture, which was established some years ago in 

 this country. A complete account of these experiments has 

 lately been very beautifully printed for private distribution, at an 

 expense of upwards of £3,000., and a copy has been most liber- 

 ally presented by the son of Colonel Beaufoy to every gentleman 

 in this county whom he supposed to be interested in the subject 

 to which the experiments refer. 



