Mile per hr. = 1·466 ft., or 44·7 cm., per sec. Lb. per cu. in. = 0·0276 kilogram per cu. cm. Kilogram per cu. cm. = 36·125 lb. per cu. in. Lb. per cu. ft. = 16·019 kilogm. per cu. mtre. Grain per gall. = 0·01426 gramme per litre. Gramme per litre = 70·116 grains per gall. Ultimate Strength│Lb. per Sq. in. „ │Tens’n.│Comp’n. ─────────────────┼───────┼─────── Wt. iron │ 50,000│ 50,000 Cast „ │ 16,000│ 95,000 Steel │ 80,000│ 70,000 Copper │ 21,000│ 50,000 Brass │ 18,000│ 10,500 Lead │ 2,500│ 7,000 Pine │ 11,000│ 6,000 Oak │ 15,000│ 10,000 Weight of Metals.│ Cub. In. │ Cub. Ft. │12 Cu. In. ─────────────────┼──────────┼──────────┼────────── Wt. iron │ 0·277│ 480│ 3·33 Cast „ │ 0·260│ 450│ 3·12 Steel │ 0·283│ 490│ 3·40 Copper │ 0·318│ 550│ 3·82 Brass │ 0·300│ 520│ 3·61 Zinc │ 0·248│ 430│ 2·98 Alumin’m │ 0.096│ 168│ 1·16 Lead │ 0.411│ 710│ 4·93 Lb. per sq. in. = 2·31 ft. water = 2·04 in. mercury = 0·0703 kilo. per sq. cm. Atmosphere = 14·7 lb. per sq. in. = 33·94 ft. water = 1·0335 „ „ Ft. hd. water = 0·433 lb. per sq. in. = 62·35 lb. per sq. ft. = 0·0304 „ „ Cub. ft. of water = 62·35 lb. = 0·0278 ton = 28·315 litres = 7·48 U.S. galls. Gall. (Imp.) = 277·27 cu. in. = 0·1604 cu. ft. = 10 lb. water = 4·544 litres. Litre = 1·76 pints = 0·22 gall. = 61 cu. in. = 0·0353 cu. ft. = 0·264 U.S. gall. Horse-power = 33,000 ft.-lb. per min. = 0·746 kilowatt = 42·4 heat units per min. Heat unit = 778 ft.-lb. = 1055 watt-sec. = 107·5 kilogrammetres = 0·252 calorie. Foot-pound = 0·00129 heat unit = 1·36 joules = 0·1383 kilogrammetres. Kilowatt = 1·34 H.P. = 44,240 ft.-lb. per min. = 3412 heat units per hour. ----- Footnote 1: It will be recognised that n is the characteristic of the logarithm of the original number. Footnote 2: The special case in which the numerator is 1, 10, or any power of 10 must be treated by the rule for reciprocals (page 27). Footnote 3: The possible need for traversing the slide, to change the indices, when using the C and D scales, is not considered as a setting. Footnote 4: The reader may be reminded that cross-multiplication of the factors in any such slide rule setting will give a constant product, _e.g._, 20 × 94·5 = 27 × 70. Footnote 5: