Pocketbook of Useful Formulæ and Memoranda
for Civil and Mechanical Engineers

319 OF ENGINEERING FOBMULÆ. Telegraph Construction, by R, S. Bbuugh— continued. For thin hollow posts of uniform thickness. V .h = 2k.f.t.x(x + 3B) gyi d = 2 x + 3 B cons^an( d — | if B vary with x. § iv. Stays, Stbuts, &c. . Let P = the horizontal strain to which a post is subjected, and h = the height of P above the ground; then the resultant moment about the ground line is m = P. h. _ If the post be sloped through an angle a, away- from the direction of the strain, then the moment is reduced to m = P . h cos. a. I If P be the resultant of any number of strains pp'p" ... acting at height hh'h"... above the ground line, the place of application of the stay is given by the equation -_S(£±£) 2 GO ’ and the strain on the stay = where 6 is the angle it makes with the horizon. If the stay be applied below x at a height y above the _ground, then 2 (j>) exerts a moment = { 2 O) O — ?/) } about the place of applica- tion of the stay, tending to bend the post at that point.