For many years scientific mechanicians and mathematicians have told us that the navigation of the air was quite possible. They have said it is only a question of motive power; “Give us a motor that is sufficiently light and strong, and we will very soon give you a practical flying machine.” A domestic goose weighs about 12 lbs., and it has been estimated that it only exerts about one-twelfth part of a horse-power in flying—that is, it is able to exert one man-power with a weight of only 12 lbs., which seems to be a very good showing for the goose. However, at the present moment, we are able to make motors which develop the power of ten men—that is, one horse-power—with less than the weight of a common barnyard fowl. Under these conditions it is quite evident that if a machine can be so designed that it will not be too wasteful in power, it must be a success. It is admitted by scientific men that all animals, such as horses, deer, dogs, and also birds, are able to develop much more dynamic energy for the carbon consumed than is possible with any thermodynamic machine that we are able to make. It may be said that many animals are able to develop the full dynamic energy of the carbon they consume, whereas the best of our motors do not develop more than 10 per cent. of the energy contained in the combustibles that they consume; but, as against this, it must be remembered that birds feed on grass, fruit, fish, etc., heavy and bulky materials containing only a small percentage of carbon, whereas with a motor we are able to use a pure hydrocarbon that has locked up in its atoms more than twenty times as much energy per pound as in the ordinary food consumed by birds. I think, in fact I assert, that the time has now arrived, having regard to the advanced state of the art in building motors, when it will be quite a simple and safe affair to erect works and turn out successful flying machines at less cost than motor cars; in fact, there is nothing that stands in the way of success to-day. The value of a successful flying machine, when considered from a purely military standpoint, cannot be over-estimated. The flying machine has come, and come to stay, and whether we like it or not, it is a problem that must be taken into serious consideration. If we are laggards we shall, unquestionably, be left behind, with a strong probability that before many years have passed over our heads, we shall have to change the colouring of our school maps.

As the newspaper accounts that we receive from the Continent give all weights and measures in the metric system, it is convenient to have some simple means at hand to convert their values into English weights and measures. I therefore give the following, which will greatly simplify matters both for French and English measurements:—

Onemetre =39·37inches.
„decimetre =3·937inc„
„centimetre = ·3937inch.
„millimetre = ·03937in„
In order to convert
Metres into inches, multiply by39·37.
Metre„ into feet,es,mul„iply „3·28.
Metre„ into yards,s,mu„iply „1·09.
Metre„ into miles,s,mul„iply „ ·00062138.
Cubic metres into cubic yards, multiply by1·30802.
Cubic„metresinto„cubicfeet,s,mul„iply „35·31658.
Miles per hour into feet per minute, multiply by88.
Miles„per hour„intofee„persecond,mult„iply „1·46663.
Miles„per hour„intokilometres per hour,„iply „1·6093.
Miles„per hour„intometres per second, „iply „ ·44702.
Miles per minute into feet per second,m„iply „88.
Pounds into grammes, multiply by453·5926.
Pou„ds in„o kilogrammes,ul„ply„ ·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,C., mu„ilpy „ ·252
Joules (mechanical equivalent), multiply by1047·96.
Foot-pounds, multiply by778.
Pounds of water into pints, multiply by ·8.
Pou„ds of „ateri „to cubic feet,tipl„ ·016046.
Pou„ds of „ateri „to litres,, multipl„ ·454587.
Pou„ds of „ateri „to cubic centimetres, multiply by454·656.
Gallons of water into pounds, multiply by10.
Ga„ons of „aterin„o cubic feet,ulti„ply „ ·16057.
Ga„ons of „aterin„o kilogrammes,„ply „4·5359.
Ga„ons of „aterin„o litres,ammes,„ply „4·54586.
Litres of water into cubic inches, multiply by61·0364.
Lit„es of„wateri„to pounds,ches, mul„ply„2·20226.
Lit„es of„wateri„to gallons, ches, mul„ply„ ·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,F., mul„ply „13·145.
Kilogramme-calories into British thermal units, multiply by3·9683.
Kilog„amme-cal„oriesi„togramme-calories,its, mul„ply „1000.
Kilog„amme-cal„oriesi„tomechanic equivalent in foot-lbs., multiply by3065·7.

APPENDIX II.

RECAPITULATION OF EARLY EXPERIMENTS.