A SMALL WATER WHEEL.--There is in the town of Meriden, Conn., a Leffel double turbine wheel, running under 240 feet fall and driving a manufactory. It uses only about one-half of a square inch of water, and runs at the marvelous speed of 3,000 revolutions per minute, or 50 revolutions per second, which is by far the most rapid rate of motion ever imparted to a water wheel. This is, also, beyond comparison the greatest fall applied to the propulsion of a wheel in America. The wheel at Meriden is of the most diminutive size, scarcely exceeding in dimensions the old-fashioned "turnip" watches which our grandfathers used to carry in their capacious vest pockets. The complete success of this wheel has attracted much attention and affords further evidence of the wide range of adaptability of the Leffel turbine. * * * * * [For the Scientific American.] SILK CULTURE. BY W. V. ANDREWS. A vague notion that silk culture ought to form one of the industrial pursuits of the American people seems to be prevalent enough; but it does not take practical hold upon anybody. The nearest approach to anything practical which we have seen, in late years--excepting, of course, what has been done in California--occurred in New York in July last, when a number of gentlemen pledged themselves, according to a report given in the _Tribune_ of July 30, "to promote the native silk trade." The gentlemen present at the meeting represented the most prominent silk manufacturing and importing houses in this country. What these gentlemen have since done towards promoting the native silk trade, I do not know, but, having pledged themselves, it is presumed they have done something. At the meeting, of which the _Tribune_ article is a report, dags, and other things, manufactured from California silk, were exhibited; and the report goes on to say that "Mr. Warren also exhibited samples of native and foreign cocoons, and of raw and thrown silk, together with the common _Cecropia_ and _Bombyx Cynthia_, species of silkworms which feed upon oak leaves. * * Also the _Bombyx Yamamai_ which feeds upon mulberry leaves; also the _Bombyx Pernyi_, of which the cocoons are early as good as the cocoons of worms fed upon mulberry leaves."