NATURAL THEOLOGY. 247 



Regarding animals in their instruments of 

 motion, we have only followed the comparison 

 through the first great division of animals into 

 beasts, birds, and fish. If it were our intention to 

 pursue the consideration further, I should take in 

 that generic distinction amongst birds, the web-foot 

 of water-fowl. It is an instance which may be 

 pointed out to a child. The utility of the web to 

 water-fowl, the inutility to land-fowl, are so ob- 



head down the stream, he must move more rapidly than the water, 

 or the water gets under the operculum of the gills, and chokes him. 

 He lies, therefore, continually with his head to the stream. We 

 may see a trout h'ing for hours stationary, whilst the stream is 

 running past him ; and they seem to remain so for days and nights. 

 In salmon-fishing, the fly is played upon the broken water, in the 

 midst of the torrent, and there the fish shows himself rising from 

 a part of the river where men could not preserve their footing, 

 though assisted by poles, or locking their arms together. When 

 the salmon leaps, he makes extraordinary exertions. Just under 

 the cataract, and against the stream, he will rush for some yards, 

 and rise out of the spray six or eight feet ; and amidst the noise of 

 the water, they may he heard striking against the rock with a 

 sound like the clapping of the hands. If they find a temporary 

 lodgement on the shelving rock, they lie quivering and preparing 

 for another somerset, until they reach the top of the cataract. This 

 exliibits not only the power of their muscles, assisted by the elasti- 

 city of their bones, but the force of instinct by which they are led 

 to seek the shallow streams for depositing their eggs. 



The porpoise will swim round and round a ship which is sailing 

 at fourteen miles an hour : a thing almost as surprising as the fly 

 circling round the horse's ears for a whole stage. 



To all this may be added, that the solid which mathematicians 

 have discovered, by refined application of the calculus, and have 

 termed " the solid of least resistance," because it is the conforma- 

 tion, which is less than an}' other affected by the resistance of any 

 medium, resembles a fish in its form. 



