Pocketbook of Useful Formulæ and Memoranda
for Civil and Mechanical Engineers

311 OF ENGINEERING FOBMULÆ. Telegraph Construction, by R. S. Brough— continued. Let i = the angle made by the wire with the horizon at the insulator. P c = — = modulus of the catenary. t ■ . ■ .Å' . I = — = the ordinate of the curve at the w insulator. Modulus of Catenary. Dip. ( . a* a* I = c "4“ —■ -4*-*4" T8c 384<C , a2 a* ae d — — a. ____ j____ i 8 c T 384 c3 46080 c® * ’ ’' i Approximately, ____________ «=|{4'+'/(3V-81 ('-)’} k =Ä + ö™"Ir- ''Given a and I, required d, d= I-c. Approximately, _____________ ' d = ^3i-v/(3jy~2i(I)2} a2 _ \ =8inei‘rl)'' Hence (1) the dip is rigidly the same for all gauges of any the same kind and quality of wire; ________ ________________________ ________________________ ____________