PBACTIOAL CARP CULTURE. 71 



escape of these gases rather than the introduction of oxygen. 



As the ponds grow older this difficulty will disappear, as the mass of 

 vegetable matter, almost inseparable from new ponds, exhausts itself by 

 decomposition, and is removed from the ponds after the fall fishing. To 

 tide over this time many devices, are resorted to, the best of which is, we 

 believe, to drive stakes firmly in several places in the pond, then bind 

 cornstocks or rye straw closely around them to a diameter of between 3 

 and 4 feet, and projecting above the water about 2 feet. If the water is 

 deep, the cornstocks or straw may be bound % the way to the top and 

 slipped over the stake, then loosely bound below and above. 



The cutting of holes in the ice, we believe to be the poorest plan of all, 

 as the water quickly congeals again and the temperature of the pond is 

 reduced. 



A plan much commended, though we can see but little virtue in it, is 

 to build a flume from a point under water, below where the water will 

 congeal too, into the most abrupt bank of the pond, far enough so that 

 a second flume at right angle to the first will stand perpendicular to the 

 water, and come up through the earth where it is high enough above the 

 water level to prevent freezing. The top of the flume then is left open, 

 and allows the gas to escape, and the oxygen to enter the pond. The dif- 

 ficulty with this plan is that the pressure of the gas is upward, and it will 

 lay heaviest next to the ice, and it will pass out of the flume only when 

 enough has accumulated to thoroughly saturate the water above the 

 flume and between it and the ice. When this condition is reached the 

 gas next to the flume will begin to pass out of the flume. But we do not 

 see that the flume is going to have any great draft on the gas from other 

 parts of the pond, than just at the mouth of the flume. As an oxygen 

 introducer, we have as little faith in the flume as we have in it for a gas 

 escape. The reason is that the surface of the water exposed to the 

 oxygen in the land end of the flume is too insignificant when compared 

 with the area of the pond, and again, being under the earth, down a 

 chimney, the oxygen has but poor opportunity to enter the water. We 

 would rather put our faith in the rye straw and cornstock plan, with the 

 proper cleaning and liming of the pond bottoms (see page 66) in the 

 fall, where they cannot lie exposed during the winter. 



