22 BULLETIN 173, U. S. NATIONAL MUSEUM 



about two-thirds of the way around the casing. The abutments on 

 the drum slide into the drum to pass the casing and are held against 

 the casing by springs. 



LEFFEL HYDRAULIC TURBINE, c. 1883 

 U.S.N.M. no, 180193 ; model ; gift of James LefEel & Co., not illustrated. 



The model represents a mixed-flow turbine, the rotor of which is in 

 two sections. The upper section is so constructed that it is in effect a 

 simple inward-flow turbine from which the water discharges radially 

 to the center. The lower section is a mixed-floAv rotor from which the 

 water discharges downward parallel to the axis of the rotor. Both 

 sections are cast together to form one rotor, and both parts receive 

 water from the same guide vanes, which are of the adjustable register 

 type. 



DOBLE WATER WHEEL, 1899 



U.S.N.M. no. 309207 ; original patent model ; transferred from the United States 

 Patent Office ; not illustrated. 



This model was submitted with the application for the patent issued 

 to William A. Doble, of San Francisco, Calif., February 7, 1899, no» 

 619149. 



The model represents a small sector of the rotor of a water wheel ta 

 which are attached three buckets, which illustrate, generally, the char- 

 acteristics of the modern tangential water-wheel bucket, i. e., the 

 notched lip, the splitter wedge, the curved face and back, and the 

 method of attaching the buckets to the rotor. (See also U.S.N.M. no. 

 310390.) 



The feature of this particular bucket is the form of the curved faces, 

 which are designed to disturb the jets of water as little as possible in 

 any way except in the plane of the wheel's rotation. The curves are 

 developed upon the theory that the water moving at high velocity has 

 a tendency to remain in one plane, called "kinetic stability", so that 

 the resultant angles of reaction caused by the reversing curves of 

 the bucket faces are not a normal result of these curves but are 

 divergent therefrom. 



PELTON WATER-WHEEL BUCKETS, 1901-1912 

 Plate 8 



U.S.N.M. nos. 310386-310390; originals; gift of the Pelton Water Wheel Co.; 

 photograph no. 4814 (group). 



U.S.N.M. no. 310386 is a rectangular bucket divided by a central 

 splitter edge into two hollow semicylindrical compartments. The 

 bucket is designed to receive and divide the jet upon the splitter edge 

 and direct the water to either side, discharging at the sides. No 

 provision is made for the flow of water in a radial direction along the 



