602 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



tlie brook, not only is the shore-line exceedingly irregular, but the bottom 

 is, for the most part, formed of small bowlders, or, if of ledge, abounds 

 in inequalities bristling with projections like a rasp, and acting on the 

 water in a manner aptly likened to the action of the rasp on wood or 

 metal. In the fish-way, great pains are commonly taken to have even sur- 

 faces. These, particularly when coated with slime, as they become after 

 a while, are as smooth and slippery as glass, presenting a minimum of 

 resistance to the descending water, which rushes across the parts with 

 unchecked velocity against the partition-walls. It may therefore be of 

 great service to give an artificial unevenuess to the floor and sides of 

 the iish-way. Large timbers crossing the floor at right angles to the 

 current will be very efficient ; but there is danger that at low stages of 

 the water they may i^roduce a succession of little cascades, to the great 

 disadvantage of such fishes as alewives. Still, they may be introduced 

 far enough apart to admit of sloping boards on the lower side. Another 

 mode, applicable to both sides and floor, is to stud them with sawed 

 strips of timber, say one or two inches in thickness and width, nailed 

 on several inches apart at right angles to the current.* 



A fish-way must be free from all such false or complicated currents as 

 would mislead or perplex the fish. It is not to be supposed that they 

 are guided by any knowledge of localities or directions, but simply by 

 the downward motion of the water. To make head against the current 

 is their steady aim, no matter whether it leads them directly forward 

 or to right or left, so long as the turns in the course are not too sharp 

 for their flexible bodies to follow. A path that appears very crooked 

 to us may be straight enough to them, and is just as good as a straight 

 path so long as it leads them constantly upward. In an eddy, the fish 

 may go round and round in the same circle at a great expense of time, 

 and a slight expense of strength too, but eifectiug nothing in progress. 

 A similar waste of time and energy occurs in following up a side-cur 

 rent which is closed above by some impassable barrier. It is well 

 known that in fish-ways consisting of series of pools, with narrow pas- 

 sage-ways from pool to pool, the greater part of each pool is occupied 

 by a large eddy, wherein certain migratory fishes, notably alewives, col- 

 lect in great numbers, and liestemming the gentle current, or carelessly 

 revolving with it, small numbers at each revolution leaving the main 

 body and shooting up into the next pool above. It is not an easy mat- 

 ter to determine their motives in pausing so long in their upward jour- 

 ney. Experts entertain diverse views. The late X. W. Foster, when 

 his attention was called to the matter, replied that such idling was in 

 perfect keeping with the behavior of the fish when passing natural ob- 

 structions, and was not to be regarded as in any degree objectionable 

 Others say that the fish do not know which way to go, and that they 



* I am indebted for this suggestion to Mr. E. A. Brackett, of Massachusetts. I do not 

 know whether the device has been tested, but it certainly appears to be a practicable 

 mode of reducing the velocity. 



