B Account of Steam-boats 



the water obliquely, instead of entering edge-wise. Each, 

 therefore, meets a sudden resistance, that reacts as a shock 

 upon the engine ; and, in a small number of paddles, these 

 shocks are not only greater, but, being less frequent, oppose a 

 much more unequal action to the moving power. Both the 

 boat and engine have been found to suffer extremely from this 

 cause. I have been informed that it has been corrected in 

 England, by inclining the plane of the paddle to the axis of the 

 wheel, so that the edge of the blade enters the water first at 

 one corner, and is immersed gradually. But in this construc- 

 tion the force is exerted obliquely, and constantly to a disad- 

 vantage ; much power will therefore be lost. 



To understand the improvement of Mr. Stevens, you have 

 only to consider the water-wheel to be sawn into three parts, 

 one of these to be removed back one-third, and another two- 

 thirds of the distance between the original place of the first 

 paddle and that which succeeds it. The water-wheel may, 

 therefore, be considered as triple ; and as each paddle will form 

 a wake little broader than itself, those of each separate wheel 

 will strike upon water at rest, in relation to the surrounding 

 fluid. The force of the blow is, however, but one-third of 

 what it is in a continuous paddle, and the succession so rapid 

 as to oppose almost a constant resistance to the engine. Such 

 a wheel, therefore, so far from rendering the motion irregular, 

 acts as a fly, and that part of the machinery, of such vital 

 importance in the boats of Fulton, is entirely omitted in those 

 of Stevens. 



. Of the engines by which this boat is propelled, I have little 

 to say : they are, in almost every respect, identical with the 

 engine of Watt. But one essential difference, that I have 

 noted, is, that the air-pump has more power than is usual. It 

 will therefore keep up a vacuum in the condenser, even when 

 the steam has a greater pressure than is usual in engines in 

 ordinary situations. In the boats of the Fulton company it 

 occasionally happened that, in anxiety to obtain speed, the 

 steam-gauge was permitted to rise to 15 inches. This did 

 not, however, cause an increase of power at all proportioned to 

 t^e increased pressure ; for an air-pump of the proportions of 



