The Steam Engine Explained and Illustrated (Seventh Edition) / With an Account of Its Invention and Progressive Improvement, and Its Application to Navigation and Railways; Including Also a Memoir of Watt

by Dionysius Lardner

which is equivalent to 19 lbs. per square inch. [Pg522]

3. What must be the diameter of a cylinder to work with a power of a hundred horses, supplied by a boiler evaporating effectively 70 cubic feet of water per hour, the mean speed of the piston being 240 feet per minute, and the steam being cut off at half stroke? Also, what will be the full pressure of steam on the piston?

Taking, as in the former examples, m = 0·1, b = 164, and r = 864, we shall have

H = 100 W = 7⁄6 V = 240,

and by the column for condensing engines, in table, p. 519, we have e′ = 6029916, where e = 0·50. Making these substitutions in

We′ = 33000 H(1 + m) + VA(b + r),

we shall have

(7⁄6) × 6029916 = 3300000 × 1·1 + 240 × 1028 × A.

Whence we find

A = 13·8;