92 AMERICAN 



than a vertical screen, which gets clogged with leaves, &c., and does 

 permit floating food to pass, which is a very important item. This 

 food consists of an immense variety of organisms, such as larvse of 

 dragon flies, minute Crustacea, water worms and beetles, young 

 fishes, aquatic snails, &c., &c. Its quantity may be increased by 

 placing a slanting boom at the mouth of the canal in such s. way as 

 to turn into it whatever the current brings down. The lower part 

 of the canal should be about 4 feet wide and 2 feet deep, and its 

 bottom should be of clean gravel, while the top is loosely covered 

 with boards. 



This is the spawning bed. Beyond comes a pool or a pond for 

 breeding-fish, and furnished with a screened outlet. Such a pool 

 should be 4 feet deep, and its bottom weedy or earthy and in no case 

 covered with gravel. Other and smaller pools may be provided for 

 the young fish of different sizes, each with a good conduit of running 

 water and a screened outlet. The hatching house must also be sup- 

 plied by a conduit of running water and with a screened outlet. 

 This building is a simple close shed with small windows which can 

 be darkened at pleasure. Within are double ranges of shallow 

 troughs, communicating, by little sluice-gates, with a supply trough, 

 which, in turn, is filled from the lower end of the conduit outside 

 the building. This lower end is fitted with three flannel strainers, 

 through which the water passes, and then enters the supply trough 

 through a little sluice-gate. These strainers should be placed at an 

 angle, so as to present much surface, and should be made to slip in 

 and out, so that they may be frequently washed. Moreover, a 

 sluice-gate should always be placed below strainers, otherwise it gets 

 clogged by leaves, &c. Each spawn-trough in the range is 18 

 inches long by 12 wide, and is separated from its neighbours by a 

 ridge l inches high. The sides may be as high as 8 inches, which 

 gives a chance to back up the water, and make a trough of that depth, 

 after the fry hatch. The water furnished to each single range by the 

 sluce-gate should be equal to an inch stream with a three inch head. 

 The water runs down the range with a gentle current about an inch 

 deep, to secure which, a fall of 1 inch in 6 feet is enough. Hatching 

 troughs are usually made of wood, with a bottom of half an inch of 

 perfectly clean gravel about the size of peas. 



To render the hatching house comfortable in the winter a stove 

 may be placed beyond the troughs. The pool, if 4 feet deep, 25 

 broad, and 40 long, will each contain several thousand breeding fish, 

 weighing from half a pound to a pound and a half. The bottom is 

 left earthy, in order that they may not deposit their spawn on it. 

 As soon as late autumn approaches the trout pair, and seek the con- 

 genial gravel of the covered spawning bed. 



For very large fish, like salmon, it is convenient to have a second 

 man, who holds the tail, giving the other full use of his left hand. 

 It is not necessary to pay attention to the different pairs of trout ; 

 males and females may be taken indiscriminately, and the produce of 



