There is no such thing, I have been told by men who were in the business of making them, as a good or even adequate fishway. There is always an imbalance between the purposes they serve and the results. All the same, fishways are the best we can do to remedy a situation that blocked great populations of fish from entry to their natural routes. They are built to try and bring back what man has taken away; though it should be said that they are as much in man’s interest as the alewife’s. Commerce is the main benefactor of their success. Fishways help open up free passage to the fish, and so increase their numbers. In a good fishway alewives can be counted or sampled. They can be taken out and transferred to other areas that are to be stocked with them. In other words, the removal of obstacles and the construction of a fish ladder means, in most cases, that a run can either be introduced or improved, and, above all, kept under control. The trouble is that they cannot be built so as to result in free-and-easy passage for the fish at all times. In fact, if they are not properly placed, they can even be a hindrance. A fishway requires engineering and research in its preparation. They vary greatly, of course, according to local conditions. A fish ladder’s length depends on the distance of the slope down which a flow is directed, or the kind of banks, rocks, or stream formation through which it is built. I imagine there are no ideal specifications. For alewives, fishway construction depends in general on the size and habits of the fish and the nature of the waters in which they travel. The great fish ladders built for salmon at the Bonneville Dam, on the Columbia River, have pools in them that are forty feet wide, sixteen feet long, and six feet deep, each being a foot above the other. One foot is no problem to the salmon, which have been known to leap as high as ten. At Stony Brook the pools on the down, or north, side of the road are ten in number and various in size, extending some distance downstream. The first six are smaller and deeper than the others, being so designed as to round a bend in the stream. Their depth, subtracting several inches of sand that keeps washing down from the road, is about two feet. [Illustration] On the upper side, above the seining pool, leading from one of the pond outlets, is a straight ladder, some twenty feet long. Its pools are four and a half feet square and twenty-eight inches deep, each being about five inches above the other, thus graduating to fit the slope.