536 



Prof. O. Reynolds on the 



about to describe ; and I am glad that I did not rest content without 

 them, for they led me to what I believe to be the discovery of refrac- 

 tion of sound by the atmosphere. 



Fig. 1. 



.The results of my first observation are shown in fig. 1. This repre- 

 sents the shape of the waves as they proceeded outwards from a point 

 near the bank of a stream about 12 feet wide. Had the water been at 

 rest there would have been semicircular rings ; as it was, the front 

 of the waves up the stream made an obtuse angle with the wall, which 

 they gradually left. The ends of the waves, it will be observed, gradually 

 died out, showing the effect of divergence. The waves proceeding down 

 the stream were, on the other hand, inclined to the wall, which they 

 approached. 



I was able to make a somewhat better observation in the Medlock, 

 near the Oxford Road Bridge, Manchester. A pipe sent a succession 

 of drops into the water at a few inches from the wall, which, falling 

 from a considerable height, made very definite waves. Fig. 2 represents 



a sketch of these waves, made on the spot : the diverging waves from the 

 ends of the direct waves, and also the bands of interference, are very 





