382 FISHING IN AMERICAN WATEES. 



BEST WATER FOR HATCHING SALMON. 



Spring water from 45 to 55 is probably the best. Spring 

 water is preferable, as being more pure than river water even 

 after being filtered, while its temperature is more equable, 

 being nearer the same throughout the year. Too much sur- 

 face or rain water is injurious, containing less vitality for 

 game fish, but more predaceous insects, so that their larvae 

 may be mixed, with the eggs in the hatching-boxes, and prey 

 on the spawn before it is hatched. 



In situations where spring water can not be obtained in 

 sufficient quantities, the river water should pass through a 

 filter of sand and gravel. If the spring is large enough and 

 the ground suitable, it may be divided into artificial rills, 

 with a pipe of two inches run of water to each. Under all 

 circumstances, a gentle, equable, and pure current is indis- 

 -pensable. 



HATCHING-BOXES FOR THE INCUBATION OF THE EGGS OF SAL- 

 MON OR TROUT, AS ADOPTED BY THE COLLEGE OF FRANCE. 



These boxes are fed from a horizontal pipe two inches in 

 diameter, by faucets tapping it at every tier of five boxes ; 

 and to break the force of the jet so that it will not derange 

 the ova in the first box, and to assist in aeration, a perforated 

 zinc cap is sometimes placed before it, as the object is to 

 maintain a regular movement of the current throughout the 

 tier of boxes, which are about six feet long and two and a 

 half wide. A constant flow of water, of nearly equal temper- 

 ature, through the boxes is a necessity. At Huningue, in 

 France, all the hatching-boxes are in a well-ventilated build- 

 ing ; and as hatching-time continues from October until Feb- 

 ruary, a cover to the hatching-boxes is essential ; and in En- 

 gland, to protect the ova from thieves, Mr. Francis recom- 

 mended a cover of perforated zinc, with the ends which are 

 above the water of zinc also ; and in order to regulate the 

 temperature of the water, the horizontal pipe should be sup- 



