67
OF ENGINEERING FOBMULÆ.
Eabthwokk Tables. (General De Lisle, R.E.)
Tables I. and II. give the cubic contents of a
prismoid in terms of the unit of measurement,
that is cubic metres from metres, cubic feet from
feet, cubic inches from inches, &c.
Tables III. and IV. are adapted for English
railway practice, giving cubic yards from measure-
ments iu feet.
Tables V. and VI. give the correction for differ-
ence of width when the latter is not uniform from
end to end of the prismoid, and are to be used
with any of the first four Tables.
2. In all these Tables the argument is the
lesser height h
greater height ~ If
decimal corresponding to
= v, of which the first place is to be found in
the left-hand column, the second at the top of the
columns, and the difference for the third is found
by simple interpolation.
3. The dimensions must in all cases be those
which give the true area of the end sections as
shown in Figs. 1, 2, 3, 4, where in Fig. 1 H is
the mean of the two side heights h h,’; iu Fig. 2,
W is the mean of the top and bottom heights.
In the end sections of a prismoid, the greater
height or width is denoted by a capital letter.
4. To find thø true mean width W„, when the
width is not uniform.
¥ 2