Handbook of Civil Engineering Calculations

FIGURE 10

where Am = area of center section.
Compute Am. Note that each coordinate of the center section of a prismoid is the arith-
metic mean of the corresponding coordinates of the end sections. Thus, Am = [30(40 + 70)

• (36 - 30)70]/2 = 1860 ft^2 (172.8 m^2 ).

4. Compute the volume of earthwork
   Using Eq. 15 gives V= 100(1504 + 4 x I860 + 2240)/[6(27)] = 6904 yd^3 (5278.8 m^3 ).

DETERMINATION OFAZIMUTH OFA STAR

BY FIELD ASTRONOMY

An observation of the sun was made at a latitude of 41°20'N. The altitude of the center of
the sun, after correction for refraction and parallax, was 46°48'. By consulting a solar

Grade

Ground

Grade