One metre = 39·37 inches. „ decimetre = 3·937 „ „ centimetre = ·3937 inch. „ millimetre = ·03937 „ In order to convert Metres into inches, multiply by 39·37. „ feet, „ „ 3·28. „ yards, „ „ 1·09. „ miles, „ „ ·00062138. Cubic metres into cubic yards, multiply by 1·30802. „ „ feet, „ „ 35·31658. Miles per hour into feet per minute, multiply by 88. „ „ „ second, „ „ 1·46663. „ „ kilometres per hour, „ „ 1·6093. „ „ metres per second, „ „ ·44702. Miles per minute into feet per second, „ „ 88. Pounds into grammes, multiply by 453·5926. „ „ kilogrammes, „ „ ·45359. Pounds pressure per sq. inch into atmospheres, multiply by ·06804. British thermal units into Pounds of water, 1° C., multiply by ·55556. Kilogramme-calories, „ „ ·252 Joules (mechanical equivalent), multiply by 1047·96. Foot-pounds, multiply by 778. Pounds of water into pints, multiply by ·8. „ „ „ cubic feet, „ ·016046. „ „ „ litres, „ ·454587. „ „ „ cubic centimetres, multiply by 454·656. Gallons of water into pounds, multiply by 10. „ „ „ cubic feet, „ „ ·16057. „ „ „ kilogrammes, „ „ 4·5359. „ „ „ litres, „ „ 4·54586. Litres of water into cubic inches, multiply by 61·0364. „ „ „ pounds, „ „ 2·20226. „ „ „ gallons, „ „ ·21998. Air, 1 cubic foot weighs at 62° 532·5 grains. Air, cubic feet into pounds, 32° F., multiply by ·08073. Pounds of dry air into cubic feet, „ „ 13·145. Kilogramme-calories into British thermal units, multiply by 3·9683. „ „ „ gramme-calories, „ „ 1000. „ „ „ mechanic equivalent in foot-lbs., multiply by 3065·7. APPENDIX II. RECAPITULATION OF EARLY EXPERIMENTS. [Illustration: Fig. 74.--Photograph of a model of my machine, showing the fore and aft horizontal rudders and the superposed aeroplanes.]