616 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



mode of coustructiou (providing the requisite form be secured) uiay, iu 

 general, be with safety left to hiiu, who may hi supposed to best consult 

 his own interests in those matters. It may, however, be remarked that, 

 except in a few instances, wood is the most economical material, and, 

 where facilities exist for wetting- the structure occasionally, perhaps 

 every day or two during the drought, it will not decay for a great many 

 years. In the construction of spirals, wood is the only material that can 

 now be economically used; and that form offers peculiar facilities for 

 preservation from rot by water-soaking. 



The cost of a fish-way depends so largely on the site and on the cost 

 of material and labor in the vicinity that no general estimate can be 

 made. The cost of extended and reversed fish- ways varies more than 

 that of the spirals, on account of the great variation in the amount of 

 work required in the foundation. A few instances may be mentioned. 

 The fish-way at Union Mills, on the Saint Croix, (Plate XXIV, figs. 1, 

 2, 3, anil 4,) being about 70 feet long, 8 feet wide inside, of the Foster 

 pattern, built of solid timber, with walls about one foot thick, with an 

 extensive foundation of crib-work, in deep water, and the whole strong 

 enough to resist the heaviest freshets with logs and ice, cost $G00. 



A fish-way at Pembroke, on the Penraaqiian Eiver, about the same 

 length, 70 feet, S feet wide, of lighter material, being not exposed to great 

 floods, was built for less than $100. 



The estimates of experts on the cost of the execution of several plans 

 at Augusta on the Kennebec have ranged from $1,500 to $3,000. The 

 dam is about 18 feet high, and the river is subject to great floods. 



A stone fish-way has been built at Brunswick on the Androscoggin 

 for $1,100. It is 180 feet long, and 10 feet wide inside, to pass over a 

 dam 18 feet high. To secure its inclined floor, a considerable amount of 

 excavation of rock was required. The walls are about two feet thick 

 and the partitions about one foot, both laid iu cement. 



A spiral fish-way has been devised for the dam at Cumberland IMills 

 on the Presumpscot, over a dam about 10 feet high. The ground-plan 

 inside the walls is 21i feet long and 15 feet wiile. It is to be built of 

 pine timber and plank, worth $30 per thousand feet; and the engineer 

 of the mills, Mr. John Warren, estimates its cost at $3!35. 



The fish-ways at Lowell and Lawrence, on the Merrimack, cost about 

 $3,000 and $9,000, respectively; and that at Holyoke, on the Connecti- 

 cut, a still larger sum. 



The fish-way of 1873, at Columbia, on the Susquehanna, being a simple 

 inclined plane, 12:) feet long and G'J feet wide, with a heavy guard-crib 

 on either side, cost $11,053. 



The general introduction of the spiral form will greatly reduce the 

 cost of constructing fish-ways over such high dams as those at Lawrence 

 and Holyoke, where a large part of the expense is incurred in the 

 foundation. 



