GElNERAL INTRODUCTION 



wheels are also in use at old mills in the Catskill Mountains 

 in New York State. 



The breast wheel, which followed the overshot wheel, was de- 

 veloped in England during the latter part of the eighteenth 

 century and was used for a long number of years. It consisted 

 of a circular drum, having on its periphery a series of buckets, 

 the sheathing of the drum forming their bottom. They were 

 operated partly by gravity and partly by kinetic energy, and 

 the water was applied through a flume and controlled by gates. 

 Below these was located the " breast " which consisted of a con- 

 cave cylindrical surface of planking concentric with the wheel. 

 The clearance was very small, thus preventing the water from 

 spilling out of the buckets until it had reached the lower 

 level. This type of wheel gave an efficiency of about 70 per 

 cent. 



The wheel types described above have, nowever, now been 

 almost entirely superseded by the turbine, and are therefore 

 so nearly obsolete that they may be considered as of historical 

 interest only. While the fundamental principles of the turbine 

 may be distinguished in wheels used in the sixteenth century, 

 the principal developments were made during the last century. 

 In the turbine the water acts mainly by impulse or reaction or 

 both, and the velocity has a definite relation to the head. 



In 1823 M. Fourneyron began his experiments on the radial 

 outward-flow turbine, the first of which was installed at Pont 

 Sur TOgnon in France in 1827. Its principle consisted in an out- 

 ward discharge from a pipe to a wheel with curved buckets placed 

 outside of the apertures of discharge. The buckets, revolving 

 from the action of the water, finally discharged it at the circum- 

 ference with its force exhausted. The tube which supplied the 

 water was closed at the bottom by a concave cone surrounding the 

 wheel shaft, which passed up through it in a pipe, so as not to be 

 exposed to the water. This cone was surrounded by a number of 

 guide plates, which directed the water to the buckets in the proper 

 tangential direction. 



The axial discharge turbine was first built by Henschel & Son in 

 Germany in 1837. There has always been doubt as to whether 

 this turbine should be attributed to Jonval or to Henschel. Jon- 

 val thoroughly described the basic idea in a patent dated 1841 and 

 it is quite possible that he was working on the proposition as early 



