THE IRRIGATION AGE. 419 



the velocity due the fall, when the water really ran through the scroll 

 with only about 45 per cent, of the velocity due to the fall, and the 

 wheel was running about one-third faster than the water that drove 

 it. He did not understand the formula 



V 2 =2gh. 



but he had a table calculated by that formula which he called the 

 spouting velocity of water, and supposed that under a given head 

 water always spouted at exactly that velocity, when, in reality, it 

 never did. But, in spite of their wrong theories, some very good 

 wheels were developed previous to 1860. 



The advantage of the scroll was that it could be built at a small 

 expense out of wood, and the runner could be made from iron at any 

 country foundry. Its fault WBS that the pressure on all sides of thfe 

 runner was not the same, forcing the runner to one side and making 

 it bind against the case. This caused a loss of power and destroyed 

 the case. The next great improvement was to place the wheel in the 

 middle of a large penstock and to lead the water to the runner by a 

 series of chutes. This gave to us the American type of wheel of the 

 present time. 



One of the men who best represents this period is James Leffel, 

 of Springfield, Ohio, the patentee of the "Leffel" wheel. He was 

 an ingenious mechanic of limited education, who owned a small 

 machine shop, and became interested in the manufacture of water- 

 wheels. His theories were wrong. He believed that the water ran 

 through the stationary guides against the buckets and at first im- 

 parted what he called a direct action to the wheel, although in reality 

 the wheel was running 50 per cent, faster than the water, a fact which 

 he never discovered. He then thought that the water was caught by 

 the runner and thrown backwards in a way that imparted a reaction- 

 ary force, when in reality the wheel was driven by this last force 

 alone. The real principle of all pressure turbines was then unknown. 

 This principle may be briefly stated as follows: The water flows 

 through the stationary guides with the velocity due to one-half of the 

 fall and under the pressure due to the other half of the fall; it enters 

 without blow or shock to the runner, whose speed at the center of the 

 bucket is the same as that of the entering water, when the pressure 

 of the last half of the fall forces the water back and drives the 

 wheel from its reaction alone. This principle seems to have been 

 unknown to early builders of the American type of water-wheel. But 

 ignorance of this law did not prevent the success of James Leffel. 

 He had a miniature testing flume for testing wheels 10 inches in diam- 

 eter. It had glass sides through which he could see just how the 

 water flowed. He had a Prony brake and diminutive weir by which 

 he learned the power and capacity of his wheel. He experimented 

 upon small wheels 10 inches in diameter until he had one which he 

 considered perfect, and then he had the good sense to stick to it and 



