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

the fuel being coke; for wood, multiply the grate area (as mentioned before) by 1.4 and the grate area will be 1.4 × 9.4 = 13.16. The tube surface of course remains the same, as, when the necessary amount of heat is developed, the same surface only is enough to apply it to the water.

To obtain 779 square feet of heating surface, we see, by table 10, that it is given by

	100 tubes	17	feet long and	1¾	inch diameter,
or	100 tubes	16	feet long and	1⅞	inch diameter,
or	100 tubes	15	feet long and	2	inch diameter,
or	100 tubes	14	feet long and	2⅛	inch diameter,
or	100 tubes	12½	feet long and	2⅜	inch diameter,
or	100 tubes	12	feet long and	2½	inch diameter,

or by consulting the table, and having given the number and length, the number and diameter, or the length and diameter, we may easily find the third factor of the surface. Thus the length being eleven feet, and diameter two inches, 779 feet is obtained by

779
11 × 3.1416 × 167 = 135 tubes.

To obtain the diameter of barrel to contain 135 two inch tubes, we use the formula

D = √(A/B[n(d+c)²]
.7854).

We have already found d = 2 inches, n = 135, whence c will be by formula,

c = N
240 = 0.54,

and