314 Notices 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. a 
_ 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, whic 
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- 
