THE TRIUIVIPH OF THE AEROPLANE 



more nearly amidships. They are made sometimes of 

 wood, sometimes of steel and canvas, and are between 

 three and four feet in diameter. 



"The hull itself is formed of steel tubing; the front 

 portion is closed by a sheathing of metal which hides 

 from view the fire-grate and apparatus for heating, but 

 allows us to see a little of the coils of the boiler and all 

 of the relatively large smokestack in which it ends. 

 There is a conical vessel in front which is simply an 

 empty float, whose use is to keep the whole from sinking 

 if it should fall in the water. 



"This boiler supplies steam for an engine of be- 

 tween one and one-half horse-power, and, with its fire- 

 grate, weighs a little over five pounds. This weight is 

 exclusive of that of the engine, which weighs, with all 

 its moving parts, but twenty-six ounces. Its duty is 

 to drive the propeller wheels, which it does at rates 

 varying from 800 to 1,200, or even more, turns a minute, 

 the highest number being reached when the whole is 

 speeding freely ahead. 



"The rudder is of a shape very unlike that of a ship, 

 for it is adapted both for vertical and horizontal steer- 

 ing. The width of the wings from tip to tip is between 

 twelve and thirteen feet, and the length of the whole 

 about sixteen feet. The weight is nearly thirty pounds, 

 of which about one-fourth is contained in the machinery. 

 The engine and boilers are constructed with an almost 

 single eye to economy of weight, not of force, and are 

 very wasteful of steam, of which they spend their own 

 weight in five minutes. This steam might all be recon- 

 densed and the water re-used by proper condensing 



[285] 



