230 REPORT OF THE COMMISSIONERS OF 



were found inside, caught as they were passing through by the act of shutting off the 

 water, and the swarming of the fish at the foot of the dam was a thing of the past. In 

 a book recently published in London, the author, Sir Herbert Maxwell, Bart., under 

 the heading "The creation of new fisheries," says: 



The rivers Avonmore and Arrow form a junction in County Sligo, composing the Balli- 

 sodare river, which is interrupted by falls utterly impracticable for salmon. The proprietor 

 constructed a series of ladders or fish passes over these falls. * * * After the ladders 

 were built spawning salmon were put in above Collooney (falls) with the result that twelve years 

 later 9,750 salmon, valued at about £3,000, were taken in the fishing weir at Ballisodare. The 

 original cost of the ladders was about ^1,000 which, it will be admitted, was a moderate 

 outlay to secure such a large income, besides the value of the sporting advantages created. 



The illustration of the Irish fish ladder referred to shows it to have been built of 

 masonry, open at the top, with arms projecting inwards from alternate sides until near 

 the exit at the crest of the dam where the arms extend entirely across the inside of 

 the pass forming bulkheads with square openings on alternate sides near the floor, after 

 the manner of the openings in the improved Cail system, shown in the accompanying 

 illustration. An annual income of $15,000 from building a fishway at the cost of 

 $5,000 is a fair investment, to say nothing of the sport which it produced. 



As to the material of which fishways should be constructed, masonry is, of course, 

 the best, if it were not for the cost ; and I doubt not that in the end it would be 

 cheaper than wood. 



The illustrations of the study of a fishway for the Vienne river, France, and of the 

 Great Falls fishway in the Potomac, are introduced here to show the stability and 

 permanence of such structures when built of masonry, or masonry and iron — as are 

 all the European fishways. Our fishways are, almost without exception, built of 

 wood, the Binghamton fishway being a fair example. The crib in that structure is 

 filled with stone to anchor it; the timbers are bolted to the bottom and the planking 

 is three-inch oak, well spiked to the timbers. The ice head is covered with a solid 

 sheet of three-eight-inch iron bent to conform to the incline and securely bolted. 

 A field of ice coming down stream would run up on the ice head, at proper stage of 

 water, project beyond the apex and break of its own weight. The whole structure 

 seems massive and durable ; and it is, until the wood rots or bolts rust, and then, if not 

 promptly repaired, general decay sets in and destruction follows. 



For this reason it is probably cheaper in the end to construct a fishway, the 

 exterior anyway, of masonry at the outset, except in small streams not visited by 

 severe and powerful freshets and heavy ice, in which case a straight chute with vertical 

 sides, and arms cleated to the bottom from alternate sides, which can be completed 

 for a comparatively small sum, will serve the purpose to pass trout over a dam with 



