314 JYotices of American Steam Boats. 



feet. Maximum width of deck, including guards, sixty four feet. 

 Depth of hold, ten feet. Height of the upper deck, eleven feet. 

 Length of the great cabin, one hundred and seventy five feet. Draft 

 of water, not exceeding four feet six inches. Diameter of the wa- 

 ter-wheels, twenty two feet. Length of the same, measured on the 

 buckets, each wheel, fifteen feet. Dip of the buckets or paddles, 

 thirty seven inches. Diameter of the iron water-wheel shafts, four- 

 teen inches. Length of the crank, five feet. Length of the stroke 

 made by the piston, ten feet. Diameter of the piston, sixty six 

 inches, its superficies being equal to three thousand four hundred 

 and twenty one square inches. The gross length of the working 

 cylinder, which is placed in a vertical position, is eleven feet, ten 

 inches. Its lateral apertures, by which the steam is received and dis- 

 charged, are forty two by ten and three fourth inches. The en- 

 gine is worked by means of four circular receiving valves, each of 

 seventeen inches diameter, (two at either end of the cylinder,) and 

 four exhausting valves of the same dimensions. The diameter of the 

 main steam pipe, and side pipes, is twenty five inches. 



The entire capacity of the cylinder, deducting the space occu- 

 pied by the piston, and including one of the side apertures extending 

 to the valves, is equal to two hundred and fifty two cubic feet, which 

 is equal to one thousand eight hundred and ninety standard wine 

 gallons, or to sixty three barrels of thirty gallons each. Should the 

 engine perform twenty six revolutions or double strokes per minute,* 

 there will be exhausted 13.104 cubic feet = 3276 barrels, per min- 

 ute, and 786.240 cubic feet of steam, or 196.560 barrels, will 

 be exhausted every hour, during the time in which the engine is in 

 full motion ! But the steam is allowed to enter freely from the boiler, 

 only during a part of each stroke, the throttle valve being then closed, 

 and the steam which has previously entered the cylinder is allowed to 

 expand during the remainder of the stroke. If the pressure of 

 steam maintained in the boilers be equal to twenty pounds per square 

 inch above the mean pressure of the atmosphere, (and greater pres- 

 sure is frequently employed in these boats,) the average effective 

 pressure on the piston may be safely estimated, even with less pres- 

 sure, at about ten pounds for each square inch of its superficies. 



* The engines; of some of the Hudson River boats are often seen running at the 

 rate of twenty eight double strokes per minute, the velocity of the piston being five 

 hundred and sixty feet per minute. 



