NATURAL HISTORY OF BRITISH SALMONID&. 127 



the weir every year in the autumn. The idea was, at any rate, 

 an original one as compared with the multiplicity of kinds of 

 fixed ladders of massive build those in use in Great Britain, 

 for example. This ladder answers admirably in practice, and 

 met with entire approbation from the members of the Fish- 

 breeders' Conference which was recently held at Dresden. 

 It may therefore claim to be somewhat particularly described 

 here and brought under more general notice, especially as 

 Herr Pietsch has had the great kindness to supply for this 

 purpose the accompanying design and also give instructions in 

 the use of the ladder. 



' The wooden weir (a l> c) occupies the whole width of the 

 river about one hundred and twenty five yards. Its face (c) 

 rises perpendicularly to a height of over three yards in a low 

 vater, so that except in a high flood the difference of level 

 between the water below the dam and that above is too great 

 for salmon to overcome, and for just this reason the use of a 

 ladder is imperative. The broad dam head (a b), with gentle 

 slope, is boarded horizontally ; its ridge (a) is horizontal 

 lengthways, and without crown. Below the dam are several 

 deep pools, in which the salmon lie, and it is over one of these 

 just below the weir that the fish pass is placed. 



' The ladder (d e) has parallel sides (/), and a level bottom 

 (d e) is made of strong two and a quarter inch planks, sixteen 

 feet four inches long, three feet six inches wide. The blocks 

 (g) are placed widely apart to allow room for large salmon to 

 move about between them easily. The height of these blocks 

 corresponds with the depth of water required for salmon, and 

 the fall is that of the floor of the ladder. The ladder rests on 

 strong beams (h] and is kept in its place by several small posts 

 (/) which are let into the beams. Its upper end is supported 

 by the woodwork (k /), and the lower by the float or platform 

 (n). The woodwork (k /) close to the front of the dam (c) is 

 lower than the dam edge, and consists of the two piles (k) and 

 the supporting beam (/) mortised on to them. The beam is 

 fastened to weir by strong iron clamps (m) (one inch square), 



