56 DOMESTICATED TROUT. 



breeding is carried on on a large scale, or where dura- 

 bility, economy, or accessibility must be consulted.* 



The comparative expense of the two methods may 

 be estimated as follows : Glass grilles cost per tray 

 $3.50 each, by the quantity.! Allowing 1,250 eggs to 

 each tray,f the apparatus for hatching 100,000 eggs, 

 with glass grilles, costs $ 280. 



The expense of the patent carbonized troughs, includ- 

 ing cost of right to use them, is less than forty cents a 

 foot, for one hundred square feet. Allowing 1,000 eggs 

 to the square foot, the apparatus for hatching 100,000 

 eggs, with the carbonized troughs, costs $ 40, leaving a 

 balance of $ 240 in favor of the carbonized troughs. 



Besides this, in the country, where most of our trout 

 ponds are and will be, the wood to make the troughs, 

 and also wood to char them with, is always plenti- 

 ful and within reach, and, once prepared and placed, 

 the carbonized troughs will last no one can tell how 

 long. The perfect freedom of charcoal from fungus, 

 and its tendency to purify the water, will, I feel confi- 

 dent, make it a favorite for hatching all eggs that are 

 to be long under water. The carbonized troughs were 

 first experimented with at the writer's salmon-breed- 

 ing establishment on the Mirimichi River, where they 

 worked to perfection. They have since been used at 

 the Cold Spring Trout Ponds, and have given the most 

 complete satisfaction.! 



* See Appendix IV., p. 306. 

 f See Dr. Slack's Catalogue, p. 4. 



X The use of charcoal or carbonized wood for hatching fish 

 was patented by the writer, June 20, 1871. 



