HATCHING APPARATUS. 



69 



tier of trays above another in the hatching troughs. 

 If there is abundance of water, three or four tiers can 

 be safely used. More than this with the ordinary 

 hatching troughs would be inconvenient, as the lower 

 tier would necessarily be so deep in the 

 water. 



The advantage of this system is that it 

 economizes room, it being obvious that with 

 four sets of trays running the whole length 

 of the trough, one above another, four 

 times as many eggs can be hatched in a 

 trough as could be hatched in one set of 

 trays. This plan has been in use, I think, 

 at the United States Salmon-breeding Es- 

 tablishment in Maine, under the charge 

 of Mr. Charles G. Atkins. It is not pat- 

 ented. 



3. Williamson's Method. This is really 

 a modification of the hatching trough, but 

 as it is intended only to be used with trays, 

 and as it makes an entire change in the 

 tray system, I include it here with the 

 other methods of employing trays. Ac- 

 cording to this plan, the water is forced 

 up through these trays from the bot- 

 tom. This is accomplished, as will be 

 seen in the accompanying diagram, by 

 placing at the lower end of each compartment in the 

 troughs a cleat extending entirely across the trough, 

 and reaching from the bottom almost to the top, and 

 by placing at the upper end a similar cleat reaching 



