Pocketbook of Useful Formulæ and Memoranda
for Civil and Mechanical Engineers

.. 324 ____________________ ____________________________ MOLESWORTH'S POCKET-BOOK Electrical Formula, by Paget Higgs, LL.D., C.E., and R. S. Brough—continued. 3. The comparison of electromotive forces. 1. By the deflection method: E' _ F (tü') n' (f + w') + g E F (d) * n (/ + iv) + g' When s = s' = co , n — n' = 1, ■ and E' __ F (d') f + tv’ + g 1. E F (d) ' f + w + g' ii. By the condenser method: . d' E' _ 8in~ 2 rt' E . d ’ n ' SUb - With the for sin. — and sin. reflecting galv. d' and d may be put d 2 ’ 111. By Poggendorff’s method: (Put ft = a> in the bridge, and intercalate E in branch x): E' __ « + f + w __ (id — uf) + (a — «') E w w — w' 4. Measurement of the internal resistance of batteries. i. By the deflection method: f - F • (,n'w' + g) - F (tT) . (n w + gf) n~ F (d) - n'. F (d) ~~ ‘