Pocketbook of Useful Formulæ and Memoranda
for Civil and Mechanical Engineers

323 OK ENGINEERING FOKMULÆ. Electrical Formulae, by Paget Higgs, LL.D., C.E., and R. S. Bboügh—continued. ( w"+ w') { g +f(n + ri) } + 2nw'w" 2 { 9 + f (« + n') 1 + ri (w" + w') n(w"--w’} 3 { 9 + f In + ri') } + n (w" + ri) where h — 1 + - and n = 1 + , g = galv., and S 8 8 — shunt resistance. 111. By deflection method: where w is known resistance in circuit with de- flection d, f, g, n, and E; x is resistance with deflection d',f, g, ri, and E'. If the resistances taken with ± currents differ, the true resistance is X = 2 — Xi + x2 . When measuring great resistances, n F (d) E' When s = s' = oo, n — ri = 1, and x = ravir •(/+!? + «’)-(/' + ø)- Jd Qa) Ju Y 2