418 THE IREIGA TION A GE. 



This throwing of the water in one direction would, by its reaction, 

 force the wheel in an opposite direction, just as the shooting of a* 

 cannon throws the cannon in the opposite direction to that in which 

 the ball flies. Each of these wheels was in principle a cannon throw- 

 ing an infinite number of balls, and was moved itself by an infinite 

 number of reactions. In the model of the Andrews & Kalbach wheel 

 the water was let into the wheels by chutes or scrolls, but in actual 

 practice the chutes were rarely used. 



The first great improvement made in the reaction wheel was in 

 the addition of the scrolls or chutes. It is said that this invention 

 was due to an accident. A firm by the name of Parker Brothers was 

 engaged in the lumber business and cut its logs with an old-fashioned 

 up-and-down saw driven by a pair of wheels, but without stationary 

 guides. One day a plank fell into the open flume and was carried 

 toward the water-wheel until the lower end caught in such a position 

 as to perform the work of a stationary guide. The influence of this 

 single plank was enough to produce a perceptible increase in the 

 power. Mr. Parker was quick to detect it, and from it developed the 

 scroll. The scroll consisted of a single spiral chute which wrapped 

 entirely around the runner and carried the water into erery part of 

 the periphery of the wheel. It made the water-wheel, which he pro- 

 ceeded to manufacture and sell, the best and most successful in the 

 market. He obtained a patent on his wheel, but was unable to con- 

 trol the scroll. 



The scroll wheel is an exclusively American type of wheel The 

 Tyler wheel is a good illustration of one of the best that was made 

 forty years ago. The Ridgway wheel shows almost the only one that 

 is manufactured now. From 1850 to 1860 nine-tenths of the patents 

 on water-wheels issued 'by the United States government were issued 

 on scroll wheels, and the majority of water-wheels in use at that time 

 were of that description. The runners in both of these wheels were 

 much like those of the Risdon wheel. 



The scroll wheel at the present time is considered antiquated, but 

 it was condemned and abandoned, not on account of any fault which 

 was inherent in the principle, but because the wheels were not prop- 

 erly constructed. The writer ventures the prediction that the scroll 

 case will at some future time supersede the tub-shaped case for wheels 

 with chutes, which is adopted by all modern builders. It is more cor- 

 rect in theory, and experiments have shown that with wheels of 

 medium size the water can run through the feeder of a scroll case 

 with four times the velocity that it can run through the feeder of the 

 ordinary case, and there will be no greater loss in power or efficiency. 



The water-wheel builder prior to 1860 never understood the wheel 

 that he was building. He supposed that the water ran through the 

 chutes with the full velocity due the fall and impinged against the 

 periphery of the runners, which he knew ran with about six-tenths 



