The London Athenceum says the experiment made by the Emperor of the French to stock the waters of St. Cloud with trout hatched artificially, has met with complete success. Trout twelve months old are eight inches long, and weigh from two and a-half to three and a-half ounces. Their value in the Paris market would be from twenty to twenty-five cents. The trout thirty-three months old are from nineteen to twenty inches long, and weigh from twenty-four to forty-one ounces, and would sell at from sixty cents to a dollar and twenty cents. It is further stated that the waters at St. Cloud were never before inhabited by any species of salmynnice. The trout are extremely numerous, and promise to yield highly productive returns, in a commercial point of view. The principal object of the Emperor is to ascertain whether the production of fish by artificial means is more profitable than the cultivation of the land, taking the same superficial area in both cases.