MANUAL OF FISH-CULTURE. 



55 



of the troii^b, hinged to its sides, and, when closed, assuming the form 

 of a roof at an angle of 45°, were Anally adopted. These covers are 

 made of thin boards, g incii thick, sawed in narrow pieces, which are 

 put together so as to leave in each corner two cracks open ^ inch wide 

 for the admission of light when the covers are closed. When open they 

 may be fixed in an upright position, thus increasing the height of the 

 sides and guarding against the loss of fish by jumping out. 



Fig. 2. 



I ll 



Troughs arranged for Rearing. 



Fig. 1. plan. Fig. 2, longituflinal section. Fig. 3, cross-section near foot of trough. Fiv. 4, inlet, 

 ■with rocking gate. Fig. 5, elevation of lower end. 



a, supply-trough. 

 6. screen. 

 c. rocking gate. 

 (?, supply-pipe. 



«, ■water-'board (to spread the water and throw it down). 

 /, fish-trough. 



</, gripe, to prevent spreadin;,' of side.s. 

 k, outlet screen. 



i, hollow outlet plug. 



j, down-spout. 



k, supports. 



I, cover. 

 iii, cover open (hanging). 

 n, cover open (upright). 

 p, cover closed. 

 '/, end boards (closing aperture). 



Water is furnished through rubber or wooden pipes | inch in diame- 

 ter, and the bore of the hollow plug at the outlet is 1| inch or larger. 

 The inflow is regulated by an oscillating or rocking gate, which is set 

 to admit the desired volume of water. The trough is set with the 

 upper end an inch or two higher than the other, to facilitate cleaning 

 out. and tlie water is kept during the summer about 4 inches deep at 

 the lower end. 



