ATKINS ON FISH- WAYS. 599 



sions demanded in oar large rivers by an application of the ratio that 

 lias been adoi)ted in all successfnl fish-ways. All the successful fish-ways 

 that have come to my knowledge have been built on small rivers, 

 mainly, it should be stated, because their construction has rarel}^ been 

 attemi)ted on large rivers, and because various unfavorable circum- 

 stances, such as a dearth of fish, have interfered witii the testing of those 

 that have been built. I do not think there is an instance of a tested 

 fish-way for salmou and alewives on a river of larger size than the Saint 

 Croix, which is, in drainage-basin, equal to the Corrib, in volume not 

 much inferior, and has on its lower dam, at the head of the tide, a fish- 

 way discharging about the same quantity of water as that at Galway, 

 namely, 720 cubic feet per minute, which is about j^j part of the aver- 

 age total volume of the Saint Croix. This flsh-way has been fairly suc- 

 cessful with alewives, great crowds of which have been seen passing 

 through it, and it is. presumed that salmon, when they could not sur- 

 mount the <lam itself, passed through the fish-way, considerable numbers 

 of them being seen in the river above. The capacity of this fish-way 

 may therefore be considered sufficient for its place. 



To carry out the same ratio in the construction of a fish- way on the 

 lower Penobscot, regarding for the moment only the total volume of 

 the river, would require a capacity equal to the discharge of 5,133 cubic 

 feet of water per minute, a volume which could hardly i)ass through an 

 opening in a Smith or Foster fish-way less than two feet deep and twelve 

 feet wide. Reverting now, for a moment, to the case of the Galway sal- 

 mon-ladder, and recalling the peculiar features of its location, to which, 

 perhaps, its success was largely owing, we note that the volume of water 

 passing through it was JL. that passing over the dam. To apply the 

 same ratio on the Penobscot, we will assume that one-half the water is 

 passing over the dam ; the volume passiugthrough the fish-way must then 

 be about 6,700 cubic feet per minute, which would perhaps run through an 

 opening two feet deep and sixteen feet wide. Thus, we find that if it is 

 to conform in relative capacity to the tested fish-ways on the American 

 river nearest approaching the size of the Penobscot, or to the best for- 

 eign salmon ladder of whose performance I am informed, it must dis- 

 charge either 5,100 or 6,700 cubic feet of water per minute, and this will 

 probably require passage-ways two feet deep and twelve or sixteen feet 

 wide. I am far from afiBrming that such a scale is essential ; but it is 

 worthy of notice that in building fish-ways with passage-ways only two 

 or three feet wide on rivers of the size of the Penobscot, we are depart- 

 ing widely from the proportion heretofore found sufficient, reducing the 

 relative volume, in fact, 70 or 90 per cent., and diminishing in an unknown 

 ratio the chances of fish finding the entrance. 



A large number, perhaps the majority, of the salmon-rivers of the 

 Eastern United States are circumstanced like the Penobscot; half or 

 more of the water at the fish season passing over the dam. Others, 

 among which the Merrimack at several points is a conspicuous example, 



