[ 517 ] 



LX. On Stationary Waves in Flowing Water. — Part III. 

 By Sir William Thomson, F.R.S. 



[Continued from p. 452.] 



In No. 138 (November), p. 446, equation (6), for (gT> + 2 ) 

 read (gJ) + q 2 ). 



AS promised in Part I., we may now consider the appli- 

 cation of the principles developed in it and in Part II. 

 to the question of towing in a canal, and we shall find almost 

 surprisingly a theoretical anticipation, 49-J- years after date, 

 of Scott Russell's brilliant " Experimental Researches into the 

 Laws of certain Hydrodynamical Phenomena that accompany 

 the Motion of Floating Bodies, and have not previously been 

 reduced into Conformity with the known Laws of the Resist- 

 ance of Fluids"*, which had led to the Scottish system of 

 "fly-boat," carrying passengers on the Glasgow and Ardrossan 

 Canal, and between Edinburgh and Glasgow on the Forth 

 and Clyde Canal, at speeds of from 8 to 12 or 13 miles an 

 hourf by a horse, or a pair of horses, galloping along the 

 bank. The practical method originated from the accident of 

 a spirited horse, whose duty it was to drag a boat along at a 

 slow speed (I suppose a walking speed), taking fright and 

 running off, drawing the boat after him, and so discovering 

 that when the speed exceeded \A?D the resistance was less 

 than at lower speeds. Mr. Scott Russell's description of the 

 incident, and of how Mr. Houston took advantage for his 

 Company of his horse's discovery, is so interesting that I 

 quote it in extenso : — " Canal navigation furnishes at once the 

 most interesting illustrations of the interference of the wave, 

 and most important opportunities for the application of its 

 principles to an improved system of practice. It is to the 

 diminished anterior section of displacement, produced by 

 raising a vessel with a sudden impulse to the summit of the 

 progressive wave, that a very great improvement recently 

 introduced into canal transport owes its existence. As far 

 as I am able to learn, the isolated fact was discovered acci- 

 dentally on the Glasgow and Ardrossan Canal of small 

 dimensions. A spirited horse in the boat of William Houston 



* By John Scott Eussell, Esq., M.A., F.R.S.E. Read before the Royal 

 Society of Edinburgh on April 3, 1837, and published in the ' Transac- 

 tions ' in 1840. 



t One mile an hour is English and American reckoning of velocity, 

 which, when not at sea, signifies 1-60933 kilometres per hour, or -44/04 

 metre per second. 



Phil. Mag. S. 5. Vol. 22. No. 139. Dec. 1886. 2 N 



