44 Report of the American 



always referred to as looking down stream.) So now we are ready for 

 them at both sides, and proper strnctures thrown out from the navigation 

 chutes guiding the shad to their mouths will bring very large runs to 

 them. In Pennsylvania then, we are on the wa}^ to a good chute for a 

 low dam, and if success be assured, it will be easy to accommodate 

 things to a high one. The principle is wide capacity and low velocity. 

 But velocity increases in a very strong ratio in falling water ; it increases 

 about as the square of the fall, and the difficulty of a fishwa}^ for a high 

 dam is therefore nearly as the square of its height. 



In making a chute then, for a high dam and for shad, you must divide 

 it into a series of low dams, thus interrupting the uniformly accelerated 

 velocity so that the proportion may be directly as the height, instead of 

 as the square of the height nearl}-. There will be difficulty and expense 

 then to be overcome in the case of high dams. Difficulties from freshets, 

 difficulties from ice, but American engineers have not often been beaten, 

 and it is fair to presume they will not be beaten in this instance. Fish- 

 ways have been made which are a success for almost all other kinds of 

 migratory fishes. Mr. Brackett's improvement on Foster's being perhaps 

 the best of them. The timidity of the shad has baffled us a little at the 

 outset, but we will yet accommodate him, and fishways will be made as 

 attractive to him as to the salmon, the alewife, the rock and the eel. 



The history- of this fisher}' movement will become interesting one of 

 these days, and I read this paper in the interest of the truth of that 

 history. Its initiation and progressive steps ought to be known and 

 understood. There may be mistakes and errors of judgment. Naj', 

 there must be, because it is managed by human creatures. But let us 

 have as few mistakes and errors as possible. 



I close b}^ saying that the Pennsylvania flshwa}' is believed to be the 

 only fishway in the woild that has as yet, in appreciable numbers, 

 admitted shad ; that the first one will not admit as many as the second 

 onl}' because it is much smaller and steeper, the}' both being built on the 

 same principle ; that that principle is due to consultations held by the 

 undersigned, in the first place with Daniel Shure and Geo. M. Lanman, 

 of Pennsylvania, the latter now no more, and with Theodore Lyman and 

 Mr. Brackett, of Massachusetts, and latterly with H. J.. Reeder, James 

 Duffy and B. L. Hewit, the present Fishery Commissioners of Penn- 

 sylvania, whose orders were obeyed in the construction of the latter 

 work. There is no doubt of ultimate success, for we are moving in the 

 right direction, even if we have not struck the actual pathway. 



