66 FISH CULTURAL ASSOCIATION. 
portioned. The illustrations here given pré&ent briefly and 
graphically the principles applied in the McDonald system of 
fish-way building, 
The flexibility of the system adapts it to the widest range of 
conditions occurring in practice. An effective passage may 
be provided for the fish over obstructions, with the supply of 
water that will flow through a cross section six inches square, 
or the fish-way may be expanded so as to take the entire dis- 
charge of a river. Constructed roughly of boards, it furnishes 
at a nominal cost the means of reestablishing our innumerable 
trout streams to the natural conditions of reproduction. 
These fish-ways may be made so light as to be readily portable, 
so that, in the season when the fish are not running, they may 
be stored away under shelter and thus protected from decay or 
destruction by ice or floods. In public parks and trout pre- 
serves, where considerations of cost are not controlling, the 
fish-way may be built of iron in ornamental designs, and while 
serving its essential purpose, made to contribute to the pictur- 
esqueness of the landscape. Solidly built of stone and iron, and of 
dimensions proportioned to the volume of the stream, it may be 
made strong enough to resist the utmost force of floods and ice, 
and by furnishing an easy passage for shad, salmon and other 
anadromous species of fish, make possible the restoration and 
maintenance of our valuable river fisheries, in spite of the ob- 
structions which are the inevitable and necessary adjuncts of 
civilization. 
Asan example of construction, we have given in fig. 6a the 
elevation, and in fig. 64, the plan of a double fish-way built of 
timbers. It consists of an inclined sluice-way of boards, the 
sides and bottom of which are supported by suitable framing. 
The sluice has in this case an inclination of one foot in three, 
The upper end is let into the dam so that its upper line is flush 
with the crest line of the dam. The lower end descends to the 
water below the dam, and is firmly anchored by being secured 
by bolts either to the rocky bed of the stream, or to piles suitably 
placed, or by other suitable means. Intermediate supports may 
be provided, by trestling, as shown in the figure, by log cribs or 
by rubble masonry. The incline flume or sluice thus established 
