REPORT OF COMMISSIONERS OF INLAND FISHERIES. 91 



The two floats on either side of the houseboat are fastened rigidly 

 together with bolted timbers. The inside floats are attached to the 

 houseboat by means of D irons and eyebolts, to allow about a foot of 

 up-and-down motion. The floats are built comparatively light and 

 of cheap wood, in view of possible future change of plans as a result 

 of experience. 



Rearing boxes. — The rearing boxes are square, made of seven- 

 eighths-inch spruce tongued and grooved boards, nailed to a 2 by 3 

 inch frame with galvanized nails. The inside dimensions are 10 by 10 

 by 4 feet. The angles between adjacent sides and between the bot- 

 tom and sides are truncated by boards 9 inches wide and beveled on 

 the edges (figs. 7 and 13). The vertical corner frame pieces are 

 left projecting above the top of the box about 2 inches, to serve as 

 corner posts for fastening the box in place. Ring bolts are put into 

 the four lower inside corners of the box for use in raising the box for 

 cleaning. 



Window cases 9 by 36 inches are placed on two opposite sides of the 

 box to receive the movable window frames (figs. 5, 6, and 7). Two 

 similar removable window frames 22 inches square are placed in the 

 bottom about 3 feet from the diagonally opposite corners of the box 

 (fig. 6). The size of the mesh in these screen windows varies, accord- 

 ing to the size of the fry under experiment, from 16 to 2 meshes to 

 the inch. The material is usually woven bronze or copper wire or 

 galvanized "iron." 



In the middle of both sides of the box not having windows a broad 

 slot is cut from the top to within about 8 inches from the bottom. 

 It allows the box to be raised above the water, even though the shaft 

 beam is low (figs. 5 and 6). When the box is down the doors (seen 

 in fig. 6), which are fastened on the side of the slot referred to, are 

 fastened shut by strong outside buttons. 



It should be said here that this construction was adopted to save 

 rebuilding the floats which had formerly held canvas bags, in which 

 case the low shaft beam was not in the way. In the case of new con- 



