DIFFERENT FORMS OF SALMON LADDERS. 49 
for any injury to the mill or navigation in connection 
therewith—it has given colour to the prevailing impression 
that the construction of a pass will necessarily, or even 
probably, have a prejudicial effect on the supply of water 
for milling or navigation purposes. However direct the 
injury which the dam inflicts on the fisheries, the remote 
possibility of injury to the dam is sufficient to prevent the 
remedy of the first evil. 
The experience of the last twenty years, however, has 
shown not only the advantages accruing from the construc- 
tion of passes, but the facility with which they can often 
be erected, and the inappreciable damage they need do to 
the milling power. Although much still remains to be 
done in this direction, many good passes or ladders have 
been built over weirs in different parts of the United 
Kingdom, the system varying according to the peculiar 
circumstances of the case. Among the more successful 
passes in England and Wales, may be mentioned those 
at Penarth, Bevere, and Pool Quay on the Severn, at 
Clitheroe on the Ribble, at Acklington on the Coquet, at 
Erbistock on the Dee, at Newton Weir on the Usk, and 
at the Bran Weir on a tributary of the Usk. 
What a salmon pass can do has seldom been so strikingly 
illustrated as in the case of the Ballisodare River, County 
Sligo, Ireland. The history of the ladders on this river 
is remarkable. “Previous to 1856,” writes Mr. Francis 
Francis in his pamphlet on ‘Salmon Ladders,’? “the 
Ballisodare River, which is formed by the junction of 
two rivers—the Avonmore and the Arrow—held no salmon. 
Occasionally a few fish came into the bay, and made their 
1 Published at the /ve/d Office, 346 Strand.» I am indebted to 
Mr. Cox, the proprietor and publisher of the /7ze/d, for the use of the 
accompanying woodcuts, representing the Ballisodare ladders. 
E 
