Handbook of Railroad Construction; For the use of American engineers. / Containing the necessary rules, tables, and formulæ for the location, construction, equipment, and management of railroads, as built in the United States.

by George L. Vose

d + c = 2.54,

also,

(d + c)² = 6.45,

and

135 × 6.45 = 871+;

and allowing three fourths of the boiler cross section to be filled with tubes, we have,

4
3 of 871 = 1161;

also,

1161
.7854 = 1478,

the square root of which is 38.5 nearly, to which add 38.5
8 or 4.8 inches, (see page [359]), and we have