•j^g BULLETIN 173, U. S. NATIONAL MUSEUM 



SO that the path of the water in the buckets was a combination of 

 radial and axial flow. Francis conducted accurate tests of his tur- 

 bine, analyzed and published the results, and formulated rules for 

 turbine runner design, with the result that his name is now used to 

 identify the whole class of inward-flow, mixed-flow turbines of which 

 his was the first. The first installation of the Francis turbine was of 

 two at the Booth Cotton Mills at Lowell. The rapid and general 

 adoption of the Francis turbine led to a great many similar designs. 

 A. M. Swain (Patent no. 28314, 1860) designed the turbine known 

 by his name in 1859. About 1860 James Leffel made the greatest 

 departure from the Francis type with his double-runner turbine 

 (see below). In this the upper half of the runner is designed for 

 radial flow and the lower half for radial admission and axial dis- 

 charge. The subsequent development of large inward-flow reaction 

 turbines has been made possible by the inventions among others of 

 the conical draft tube, the spiral casing, the spreading draft tube 

 (L. F. Moody), the hydraucone (W. M. White), movable guide vanes, 

 the Kingsbury thrust bearing, and the use of rubber seal rings (for 

 high heads). The 54,000 horsepower I. P. Morris turbine of the 

 Conowingo (Md.) Station of the Philadelphia Electric Co., 89-foot 

 head (see below), and the San Franscisquito No. 2 plant of the City 

 of Los Angeles, 20,500 horsepower at 515-foot head are indications 

 of the advance. The Oak Grove plant of the Portland Railway 

 Light & Power Co., 35,000 horsepower at 850-foot head holds the 

 record (1930) for high head application of a turbine of the Francis 

 type. 



Impulse turbines and tangential water wheels. — Parallel with the 

 improvement of the reaction or pressure turbine was the development 

 of the impulse or velocity turbine, also called the tangential water 

 wheel. An impulse turbine is one driven entirely by the force of 

 the weight of the water acting through its velocity. The wheel 

 buckets are open to the atmosphere, and the discharge is unrestricted 

 so that none of the energy of the flow of water is utilized as pressure 

 energy. The first current wheel was an impulse turbine of the 

 simplest form. The Poncelet water wheel, with the stream confined 

 and directed fully upon curved buckets and with the discharge above 

 the tail water, was the beginning of the modern development. In 

 the present-day wheels of the most common type the flow of water 

 is wholly confined and is directed upon the wheel from one or two 

 adjustable nozzles. The buckets are highly developed combinations 

 of curved surfaces. 



The first departure from the undershot wheel, in impulse turbines, 

 was that of Jearum Atkins, of Vermont and Illinois, well-known 

 inventor of agricultural machinery. Atkins' turbine consisted of a 

 horizontal rotor having buckets curved as semicircles in the radial 



