. Railroad construction, theory and practice; a text-book for the use of students in colleges and technical schools, and a hand-book for the use of engineers in field and office . the rule as |-|^(91X95). In the first case the product ()could be read directly to the nearest .2 of a cubic yard, whichis unnecessarily accurate. In the other case, the product(8004) could only be obtained by estimating -^^ of a division. The computation for the prismoidal correction (see § 114),may be made similarly except that the divisor is instead of 5 5X11 7 For example, 1-1()=-^ -. Set t
. Railroad construction, theory and practice; a text-book for the use of students in colleges and technical schools, and a hand-book for the use of engineers in field and office . the rule as |-|^(91X95). In the first case the product ()could be read directly to the nearest .2 of a cubic yard, whichis unnecessarily accurate. In the other case, the product(8004) could only be obtained by estimating -^^ of a division. The computation for the prismoidal correction (see § 114),may be made similarly except that the divisor is instead of 5 5X11 7 For example, 1-1()=-^ -. Set the 324 on ^ ^^ scale B (also specially marked like 108) opposite 55 on scale A,and proceed as before. 107. Approximate volume. Irregular sections. In cross-sectioning irregular sections, the distance from the center andthe elevation above grade of every break in the cross-section must be observed. The area of the irregular sectionmay be obtained by computing the area of the trapezoids {five,in Fig. 53) and subtracting the two external triangles. For the area would be § 107. EARTHWORK. 125 hi + ki. , ki + d , d+jr , jr-hh (yr-Zr) , kr + , , hi/ b\ hrf h\. Fig. 53. Expanding this and collecting terms, of which many willcancel, we obtain 4[ Area = — xiki-\-yi(d—hi) +Xrkr+yr(jr—hr) ■{-Zr(d-kr)+ (hi + hr) \ ... (50) An examination of this formula will show a perfect regii-larity in its formation which will enable one to write out nsimilar formula for any section, no matter how irregular or howmany points there are, without any of the preliminary formula may be expressed in words as follows: A RE A equals one^-half the sum of products obtained as follows: the distance to each slope-stake times the height above grade ofthe point next inside the slope-stake; the distance to each intermediate point in turn times the height ofthe point just inside minus the height of the point just outside; finally, one-half the width of the roadbed times the sum of thes
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Keywords: ., bookauthorwebbwalt, bookcentury1900, bookdecade1920, bookyear1922
