IhdcI, an imperfect fertilizer. Tlie only means which we can 

 suggest by which these fish could he saved is the construc- 

 tion and use of the fish ponds, such as are operated on the 

 Detroit River, and thus described by Professor Milner, in 

 the Repurt of the United States Commissioner to whom we 

 are indebted for tha accompanying plate. 



The "Ponds" of Detroit River. 



"These fisheries, knoAvn as ponds, are among the most ex- 

 tensive establishments of the lake. Large numbers of 

 white-fish arc kept alive in them, from the fall of the year, 

 U) late in the winter, when they are taken out, and sold in 

 the market at good prices. The best ponds are situated at 

 Islands in the middle of the River, where there is an ample 

 circulation of water, keeping the fish in vigorous, healthy 

 condition for months. 



"The ])ond is merely an inclosure in the river, made by 

 driving piles close together, and afterward sheathing the in- 

 side witli })lanks, leaving joints of three quarters of an inch 

 in width, to allow the free circulation of water through the 

 pond. At one end of the pond a gate is put in, hinged at 

 the bottom of the river to a mudsill, and the upper portion, 

 floating at an angle of about 45°, projects a foot or more 

 above tlie surface, closing the entrance to the pond. By 

 ])ushing tlie gate bcneatli the surface, with a pole, it is 

 opened to the extent of one, two, three or more feet, accord- 

 ing to the deptli the toj) of the gate is pushed down. The 

 accompanying plate represents one of the best arranged and 

 conducted fisheries on Detroit River. The buildings for the 

 men, tlie Tiet house, and the store house, with the windlass 

 sheds, are all in view. It will be seen that the fishing is 

 carried on by sweeping a seine in front of the pond, that is 

 drawn in by horse power. When the brails come on shore 

 the men liaul in the seine until the bag is reached, when the 

 leads are tiirown over the top of the gate, which is then 

 pushed down, leaving an open space at the surface, of two 

 feet, thougli which the fish are emptied into the pond, with- 

 out being touclied by the hand or taken above water. 



