Mr liedfield on American Steam-Boats. 59 



showing a force exerted upon the engine which is equal to the 

 power of eight hundred and sixty-two horses. From this re- 

 sult we are to deduct the power necessary for moving the en- 

 gine, or that required for overcoming the friction and resistance 

 of its parts, which is comparatively less in engines of this mag- 

 nitude, working on such an extended crank, than in the average 

 of smaller engines. We will estimate it, however, as equal to 

 one-third of the force applied, which gives the effective work- 

 ing-power of the engine as equal to that of five hundred and se- 

 venty-five horses. An engineer with whom I have conferred, 

 and under whose direction several of the engines in these boats 

 have been constructed, estimates the net effective pressure, 

 ea^dusive of all deduction Jbrjriction, &c. as equal to twelve 

 pounds for every square inch of the piston. This may be 

 nearer the truth, and gives the working-power of this engine 

 as equal to six hundred and forty-six horses. Such results may 

 at first view appear to be of a startling character, even to pro- 

 fessional readers, but having been arrived at by gradual ap- 

 proximations, they seem hardly to have attracted the attention, 

 either of men of science or practical engineers. 



The following may be given as a summary statement of the 

 principal dimensions of the other boats which have been named, 

 and which, if not minutely correct in all its particulars, is suffi- 

 ciently so for purposes of general information. The Cham- 

 plain, a new boat, is 180 feet in length, 28 feet beam on the 

 water line, and has two engines of 42 inches cylinder, and 

 10 feet stroke, which, with wheels of 22 feet, run from 26 to 

 28 revolutions per minute. Tlie Erie, also a new boat, is of 

 the same size, and somewhat greater power, her cylinders being 

 of 44 inches diameter*. The North America is 218 feet in 

 length, including a cut-water bow (which has also been affixed 

 to most of the other boats), 30 feet beam, and has also two 

 engines, with cylinders of 44 inches diameter, and 8 feet stroke. 



• These two boats run to the City of Troy, a prosperous and beautiful 

 town, situated six miles above Albany. A large lithographic drawing of 

 these steam-boats, including also a sketch of the scenery in the Highlands of 

 the Hudson, near the mountain called Anihonj/'s Nose, has been published by 

 the company owning the boats. 



