50 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [8] 



single 2-iuch plank, is fastened securely to the sides, h h, the posts, 

 h h, and the return buckets, m m, thus completing the construction. 



We have here realized in timber the same construction and secured 

 the same control of the descending current as shown in the experimen- 

 tal apparatus (Fig. 5). The course of the water is shown by the arrows. 

 When a sufficient supplj^ of water is brought to the head of the fish- 

 way we will have an average depth of waterway above the floor d of 

 10 to 12 inches. Any excess of water over the amount needed to fill the 

 fishway will be shed over the sides, and the fishway will continue in ef- 

 ficient operation in any stage of water. 



In the drawings (Figs. 7, 8, and 9) the open spaces between the bulk- 

 heads i if &c., and also the head of the fishway, where the water passes 

 under the floor d, directly from the dam, are represented as guarded 

 by a wrought-iron grating. This is only necessary where the exposed 

 position requires that the weak points be protected from injury by ice 

 or drifting timbers. The grating may be dispensed with where other 

 safeguards are made use of. 



7. Location. 



The proper setting or location of the fishway is a matter of prime im- 

 portance to secure satisfactory operation. Where the cost of the con- 

 struction is considerable the location should be made under the direc- 

 tion of a competent engineer and after a careful study of the locality. 



In all cases the following conditions are to be observed in the con- 

 struction : (1) The water capacity of the fishway must be in proportion 

 to the volume of the stream. The more water we can discharge through 

 the fishway the more satisfactory it will be in operation. (2) The upper 

 end of the fishway must be set at such level as to run full at ordinarj^ 

 spring stages of the stream. (3} The discharge from the fishway should 

 be made close to the face of the dam. (4) The fishway must be so lo- 

 cated as to be sheltered from ice and drift, or, wlien this is impracticable, 

 it must be built strong enough to resist injury. Where these conditions 

 are realized in the construction complete satisfaction in operation may 

 be expected. 



In Figs. 10, n, and 12 are i)resented three i)lans of actual construc- 

 tions, which will furnish useful suggestions as to location. 



Fig. 10 shows plan of fishway on the Rappahannock River, near Fred- 

 ericksburg, Va. The water is brought to the head of the fishway by a 

 culvert piercing the flood- wall. The fishway is built on a slope of 1 foot 

 in 3, and in two sections, so as to bring the discharge close to the abut- 

 ment. This has been in successful operation two seasons. 



Fig. 11 shows plan of fishway at Bosher's Dam, on James River, Vir- 

 ginia, miles above Richmond. This is a later and improved design, 

 though embodying the same principles of construction as shown in the 

 Fredericksburg way. Here advantage was taken of the locality to 

 shelter the way behind the high flood shown in the drawing. Two 



