110 NOTES AND 



Columbia, and is very shallow and bad, particularly at the upper end. Since 

 these operations, the inhabitants above complain most grievously about the di- 

 minution of salmon, which formerly abounded in the Cayuga and Seneca Lakes, 

 and their tributary streams, and they attribute it to the dam. Now it is well 

 known, that a rolling dam particularly, cannot oppose any serious impediment 

 against the ascent of this fish. When the waters are high, several vessels avoid 

 the canal and pass over the dam. It is indeed now understood, that the salient 

 powers ascribed to the salmon, have been greatly overrated ; and that it is a vul- 

 gar error to suppose, that the salmon coils himself up in the form of a ring, and 

 seizing his tail in his mouth, by the strained violence of an elastic spring over- 

 leaps the highest ascent in an aerial somerset. On the contrary, in every in- 

 stance where he ascends those elevations called salmon leaps, he does it by swim- 

 ming up and over the face and brow of the water-fall, penetrating through the 

 interior of the descending body of water, by means of his vast muscular power 

 operating on the action of his tail ; and lie affects his passage when the stream 

 is very much flooded, and a large unbroken mass of water is descending. With- 

 out such a solid column of water, his ascent would be physically impossible ; at 

 these times the water, as in all cases of flood, is highly discoloured, and so 

 dartingly quick is the ascent of the fish, as rather to resemble the transient gleam 

 of a passing shadow over the water, than a real substance penetrating through it . 

 (Philosophical Magazine, vol. 34.) It is nevertheless obvious, that this dam 

 could not prevent the ascent of salmon : some other cause must be found out 

 The salmon is a very timid fish. In April, May, and June, 1810, the year af- 

 ter the canal was used, near two hundred boats had passed through it. The 

 improved navigation had greatly increased the number of vessels which used it. 

 The width of the river at the dam is about twenty-three rods. In salt water 

 creeks, where no obstacles exist, the same complaint is made of the scarcity of 

 fish. Newtown creek, which heads about four miles from the east river, by an 

 uninterrupted navigation, is, when compared with its former abundance, now al- 

 most destitute of fish. The principal cause of the diminution is, in the augmenta- 

 tion of the number of boats, and the increase of the navigation, which have fright- 

 ened the fish away. 



Other reasons may be assigned of great weight. The cultivation of the coun- 

 try has had a prodigious effect in producing this diminution. Some species of 

 fish subsist on the larva of insects and worms. The cutting down of trees, the 

 drying up of swamps, marshes, the ploughing of land, and the exposure of the 

 soil to the influence of the sun, have lessened these sources of subsistence. The 

 streams and rivers have also been diminished in size, some of them have been 

 entirely dried up. The fountains and springs which furnished cool retreats for 

 the deposite of their spawn, are destroyed The alluvial deposites have rJpc> 



