BY JOHN H. COOPER. As a matter of general information, supplementing the very elaborate communication on the historical development of the type of water wheels known as the " tangential " or impulse water wheei, which was lately published in this Journal,* the following record of tests of the efficiency of a modified form of the tangential water wheel, manufactured by James Leffel & Co., Springfield, O., which were made in the mechanical engineering laboratory of the Ohio State University, under the direction of Prof E. A. Hitchcock, Director, will be found to make an interestingcontribution to the history of this class of machines. A brief description of the "Cascade " wheel is introduced, to give the reader an idea of its distinctive features. It is adapted, like others of its class, for use where small quantities of water under very high heads are available. This wheel has two separate sets of buckets. These buckets are located alternately on each side of a central, sharp, continuous, dividing ridge, projecting a little in front of the entering edge .of the buckets. This dividing ridge has a sharp, cutting edge, which serves to divide the jet of water before it touches or reaches the buckets, and to keep it continuously divided in two equal portions, so that each portion of this single jet is received separately on each side of the dividing ridge. One-half of the jet is therefore received by one series of buckets independently of the other half, which is received by the other series. Each series of buckets on each side of this continuous dividing edge is so arranged that no two come opposite each other, and, as a consequence, the buckets of each series catch the water alternately. The claim is made for this alternating arrangement of buckets that it secures greater steadiness of motion, since *Jour. Frank. Inst.