CATALOG OF THE MECHANICAL COLLECTIONS 19 



direction, straight sided in the axial direction, and open to the 

 atmosphere above and below. The water entered the wheel from a 

 scroll casing surrounding it. Flat guide vanes within the casing 

 ■directed the water into the buckets in smooth continuous streams at 

 several points around the periphery. The speed of the rotor was 

 such that the water reached the inner edge of the bucket with little 

 velocity in the radial direction, and discharged by falling through 

 the lower side of the bucket space. Atkins applied for a patent in 

 1853, about the time that Girard in England was perfecting his turbine 

 of similar design. This type of turbine has been popular abroad, but 

 it has never been widely used in the United States, where the impulse 

 turbine most generally used is the tangential water wheel. 



The simplest form of the tangential water wheel was the "hurdy- 

 gurdy," a large wooden wheel carrying buckets of angular boxlike 

 construction into which water was directed from one or two fixed 

 nozzles located near the bottom of the wheel. These wheels were 

 widely used in the mountain settlements of the Pacific coast where 

 high-head water powers were developed for mining operations. The 

 wheels were developed there experimentally, and various stories are 

 told of this development. The first wheels are said to have been 

 wagon wheels with flat floats or box buckets bolted to the rims of the 

 wheels. The wagon wheels gave way to wooden centers, wide-rimmed 

 wooden wheels, and, later, iron wheels. The buckets then were made 

 as curved bowls with cut-out lips to aid discharge (Knight, 1870), 

 and the split bucket is said to have been the result of an accident 

 in which a wheel slipped sideways on its shaft so that the jet struck 

 the edge of the bowl instead of the center, with the result that the 

 speed of the wheel increased. J. Moore, 1874, and L. A. Pelton, about 

 1877, designed split buckets, and Pelton after some success in selling 

 and installing wheels of his design, including the installation of the 

 first impulse turbine-electric generating unit at Aspen, Colo., in 1885, 

 sold his business to the founders of the Pelton Water Wheel Co. m 

 1887. Experiments conducted by Kalph T. Brown and Professor 

 Hesse at the University of California resulted in the design from 

 theoretical analysis of a bucket similar to Pelton's, and the report of 

 these experiments, published in 1883, was the first literature on the 

 subject of the design of impulse water wheels. The buckets subse- 

 quently developed in form through the work of Hesse, Abner Doble 

 (1889), Dodd (1889), and Hug (1897). The present type has ellip- 

 soidal back and face surfaces, central spitter edge, and notched lip, 

 substantially as developed by Doble by 1899 (see below) and has the 

 chain type of attaching-lug developed about 1907 by the Pelton Water 

 Wheel Co. The method of controlling the jets, at first merely by 

 gate valves, was developed through butterfly valves, tongue nozzles 

 in which one side of rectangular nozzles was hinged like a tongue, 



