Pocketbook of Useful Formulæ and Memoranda
for Civil and Mechanical Engineers

420 Molesworth’s pocket-book Friction ok Plane Surfaces. Mean Coefficient of Friction of Repose. Nature of Unguent. Wood on wood .. .. ‘50 ’68 Metal on metal .. .. -18 —• Wood on metal . . .. ' 60 ■ 65 Matted hemp on wood .. • 63 • 87 Bole leather on wood or iron • 62 • 80 Belting on iron pulleys .. ’54, —। Belting on wood „ .. ’47 — Stones on stones or bricks • 71 — Stones on wrought iron .. ’45 — Wood on stones .. .. '60 — The coefficient of friction of motion in moat cases = the coefficient of repose X 0'7 ; coefficient X pressure = power required to overcome the friction. Büle for finding the Weight of Castings oe Forgings by the Weight of their Patterns. Weight of pattem in) cCa8tiron. well-dried pine .. J „ „ x 17'1 ?= wrought iron. „ ,, xl7'6 = steel. „ „ X19 —copper. „ „ x25 —lead.