164 American Fisheries Society. 



overflowed," is the statement of an experienced western man 

 .... "I have seen suckers and grayling (Williamson's whitefish) ; 

 but trout are too smart, and are never taken in irrigation ditches" 

 (Ibid p. 101). A well-known ranchman in Western Alberta de- 

 clared : "There should be screens at the headgates. They would 

 not clog as there is not enough rubbish to cause much bother." 

 (Ibid, p. 99). 



Twenty-five years ago the State of Maine tried to enforce 

 a law requiring screens to be installed at the outlets of all lakes 

 and ponds (See N. Y. Fishing Gazette, June 25, 1897). The 

 amount of leaves and rootlets floating in the water varies in 

 different localities; but the device invented by State Warden 

 W. F. Scott (Montana), and described in Forest and Stream, 

 February 14, 1903, meets the most serious objections. It is 

 simply an eight-bladed paddle-wheel, placed in a short flume at 

 the head of the ditch, the projecting end of the center octagon 

 shaft working in a slot-bearing at each side. If very wide, two 

 flumes are advisable, and they so work that any large materials 

 or hard substances pass under the paddles because the whole 

 wheel rises, the axle being lifted up in the vertical slot at each 

 side. Frightened away, it is claimed, by the splashing of the 

 paddle blades, fish remain at the upper side of the device at the 

 head of the ditch. A modification of this paddle device has been 

 suggested, viz., a barrel-shaped frame covered with small-meshed 

 wire netting, and fitting the flume closely. I think it was Dr. 

 Henshall who proposed the barrel screen, and the use of the 

 paddle for motor-power. If the pulley be placed on the projecting 

 shafts outside the flume, and the belts crossed, then the paddles 

 work in a direction opposite to that of the barrel screen at the 

 entrance to the ditch. By this arrangement the device is self- 

 cleaning, all leaves and rubbish being carried over, and the fish 

 prevented from finding a passage down. In very wide ditches 

 two flumes and a double apparatus are advisable. 



A patent screen, invented by Mr. W. Parsons (U. S. Patent 

 1166628) resembles the Scott device; but the patent of Mr. 

 Dreher, Detroit, Mich., (U. S. Patent 1150348) is provided with 

 a paddle bearing long prongs to deter the approach of the fish. 

 A more elaborate device is that of Mr. H. Broberg (U. S. Patent 

 1147301) which rotates on a vertical not a horizontal shaft, and 



