CHEAP FIXTUEES FOR THE HATCHING OF SALMON. 947 



this respect, the site must be rejected. It would be well, also, to visit the 

 place in time of flood and, if in a very cold climate, in severe winter 

 weather, to know what dangers are to be guarded against on those 

 scores. 



The volume of water necessary will depend on several circumstances, 

 mainly on the following: 1st, the proposed capacity of the establishment; 

 2d, the temperature of the water ; 3d, its character as to aeration ; 4th, the 

 facilities existing in the house for the aeration and repeated use of the 

 water. With water of the highest quality and low temperature and with 

 unlimited facilities for aeration, possibly a gallon a minute or even less 

 can be made to answer for the incubation of 100,000 eggs of salmon. As 

 the temperature rises or the facilities for aeration are curtailed, a larger 

 volume becomes necessary. In case of spring water, cooled only to 40°, and 

 aerated only by exposure to air in a pool of about a square rod surface, with no 

 facilities in the house for aeration, and with the eggs and fry crowded in 

 the troughs at the rate of 4,000 per square foot, 4 gallons a minute is the 

 least that can be trusted to support that number, (100,000,) while 6, 8, or 10 

 gallons per minute would be much better. While the minimum is, as stated 

 above, possibly less than a gallon a minute, no novice can be advised to trust 

 to less than 3 gallons per minute for each hundred thousand eggs or fish under 

 the most favorable circumstances. These statements are about as definite as 

 can be made. The question of volume must be decided for each case accord- 

 ing to the peculiar circumstances existing, and the novice must first acquaint 

 himself with the mode of arranging the fixtures in the house, and es- 

 pecially with the means and facilities for aeration, for which directions 

 will be given below, and then study the possibilities of the proposed site. 

 It should be borne in mind that the volumes of water stated above are 

 strictly minimum quantities, meant to apply to the very lowest stage of 

 water that can possibly occur during the hatching season. 



If the water supply is to be drawn from a small brook or a spring, it 

 will be necessary to measure the volume carefully. The following is an 

 easy and accurate mode, applicable to most cases. Take a wide board 

 one inch thick, (or two or three of them carefully jointed or matched,) and 

 bore a smooth inch hole through the middle of it. With this make a 

 tight dam across the stream so that all the water will have to flow through 

 the hole. If the water on the upper side rises just to the top of the hole, 

 it indicates a volume of 2.3 gallons per minute ; a rise of half an inch 

 above the top of the hole indicates a volume of 3 J gallons per minute ; 

 2 inches rise, 5 gallons per minute; 3 inches, 6 gallons per minute; 6 

 inches, 8 gallons per minute; 12 inches, 12 gallons per minute. If two 

 one-inch holes are bored, the same rise will of course indicate twice the 

 volume. The volume vented by holes of different sizes is in proportion 

 to the squares of their diameters ; thus a two-inch hole vents four times 



