AN IMPOSSIBLE PERFORMANCE. 213 



absolutely impossible, and that the bird merely dives and swims 

 xinder water like other aquatic birds. 



In a question of this sort, the point at issue is to be decided 

 not so much by the results of casual observation, in which from 

 the very nature of the case all are liable to error, as by 

 an appeal to the invariable laws of nature. Still, what ought 

 to be, and even what must be, has to give way when con- 

 fronted with a clear and indisputable case of what is; and on 

 this question it must be admitted there is what looks like very 

 reliable evidence of the impossible performance. Here, for 

 example, is Mr. St. John, who affirms in the most positive 

 manner that he has himself seen the Dipper walk deliberately 

 off from his stone down into the water, and walk and run about 

 on the gravel at the bottom, scratching with his feet among the 

 small stones, and pecking aay a t all the small insects and ani- 

 malculse which it could dislodge. " On two or three occasions," 

 he continues, "I have witnessed this act of the Water-ousel, 

 and have most distinctly seen the bird walking and feeding in 

 this manner under the pellucid waters of a Highland burn." 



Against this testimony of Mr. St. John's there is that of 

 Mr. Macgillivray, an equally careful observer, who also speaks 

 from personal observation. He says distinctly that in one or two 

 instances where he has been able to perceive the bird under water, it 

 appeared to tumble about in a very extraordinary manner, with 

 its head downward, as if pecking something, and at the same time 

 making great exertion with both legs and wings. The general 

 direction of the body was obliquely downwards, and the 

 exertions the bird was making were evidently to counteract its 

 natural buoyancy and to keep itself at the bottom. Mr. Mac- 

 gillivray says, indeed, that the movements of the bird under water 

 are precisely similar to those of the Divers, Cormorants, and Mer- 

 gansers, which are effected by the joint action of both wings and 

 legs, and are rather to be described as flying than as bond fide 

 swimming ; and he further states that the bird does not proceed 

 to any great distance under water, but, alighting on some spot, 

 sinks, and soon reappears in the immediate neighbourhood, when 

 it either dives again, or rises on the wing to drop somewhere 

 else in the water, or to take up its favourite position on some in- 

 sulated stone in the middle of the brook. 



In so far as observation is concerned, therefore, there are 



