THE FLASH-WMEliL, FOll KAISING "WATER. 



2-31 



THE FLASH-WHEEL 



is employed with great advantage where the quantity of 

 water is large, and is to be raised to a small height, as in 

 draining marshes and swamps. It is like an undershot 

 wheel with its motion reversed; in fig. 258 the ar- 

 rows show the direction of the current when driven up- 

 ward. It must, of course, be made to fit the channel 

 closely, without touching and causing friction. In its best 

 form, its paddles incline backward, so as to be nearly up- 



Fig. 258. 



Flash or fen ichcclfor raising ivater rapidly short distances. 



right at the time the water is discharged from them into 

 the upper channel. It has been much used in Holland, 

 where it is driven by wind-mills, for draining the surface- 

 water oif from embanked meadows. In England, it has 

 been driven by steam-engines ; and in one instance, an 

 eighty-horse-power engine, with ten bushels of coal, raised 

 9,840 tons of water six feet and seven inches high, in an 

 hour. This is equal to more than 29,000 lbs. raised one 

 foot per minute by each horse-power, showing tliat very 

 little force is lost by friction in the use of the flash-wheeU 



