Chemical and Physical Papers. 61 



Fourth.— Locate a point on the line GH in both directions from 

 the point A at a distance equal to one-half the sum of the two 

 radii X and D from the point A. 



Fifth. — With an arc of a circle determined by the three points 

 B, H and F connect such three points. 



Sixth. — Also, with an arc of a circle determined by the three 

 points C, G and E, connect the three said points C, G and E. 



An engine builded with the outline of the casing constructed on 

 this curve allows no escape of power and allows the application of 

 the power on the ends of levers far from the fulcrum, and so little 

 speed is needed, and consequently little wear on the machinery 

 results. 



With the same mechanism water power can be utilized to the 

 very limit of its potential efficiency, as no water can escape until 

 the machine turns, so a small tiow with a high head can be readily 

 controlled. 



In fact, any kind of a power engine may be so constructed which 

 will allow high or low speed with safety, and without the wrench 

 and strain on the machinery found in the slide-valve engine. 



A model of such an engine constructed for the use of steam is 

 now in the possession of the secretary of this Society, and by actual 

 test verifies the principles above stated. 



