668 SCIENTIFIC PROBLEMS OF THE FUTURE 



The invention of balloons lias no doubt given some impetus to the 

 study of the subject, and navigable balloons of increasing speed and 

 importance are at this moment being made on the Continent. Thus, 

 the latest improved machine now under construction for the French 

 war office is expected to obtam a speed of 40 kilometers, or nearly 25 

 miles, an hour. The navigable balloon, however, at its best, will, on a 

 broad view, provide nothing more than a convenient stepping-stone or 

 intermediate stage, to pave the way for the flying machine proper, 

 which will certainly follow and supersede it in the future. Meanwhile, 

 unless some bold inventor should bring forward speedily a true flying 

 machine, we may expect to see successive modifications in, or progres- 

 sive forms of, navigable balloons introducing the principle of the flying 

 machine proper gradually and tentatively. 



Thus, whereas at present all the weight is sustained by the balloon, 

 in future models the greater part of the weight only will probably be 

 gas-sustained, and the rest of the lifting power and necessary changes 

 of elevation will be provided for by the lifting action of air screws. 

 By and by the air screw, or air propulsion in some form, will predomi- 

 nate. The balloon will be first reduced to an auxiliary appliance, and 

 then laid aside altogether. The result, of course, of its final rejection 

 will be an immense gain in a greatly diminished resistance and a corre- 

 sponding increase in speed and power. 



When first it became my duty to study this subject, some thirteen 

 or fourteen years ago, the flying machine proper was a demonstrable 

 impossibility in the then condition of mechanical science. Since that 

 time the problem has been attacked and its great acknowledged diffi- 

 culties steadily minimized from three diflerent quarters simultaneously. 

 The net result has been to reduce it to far more moderate and manage- 

 able dimensions; and if a corresi)on(Ung rate of progress is to be main- 

 tained for another thirteen or fourteen years, this great problem is 

 morally certain of solution. 



I do not propose here to consider the subject in any detail or to give 

 any figures or calculations upon it, but rather to confine myself to such 

 observations on its leading conditions as are necessary to explain and 

 support the above statement and to indicate generally our present 

 position on the whole question. 



The problem of aerial navigation by flying machines hinges prima- 

 rily, of course, on the ratio of power developed by, to weight involved 

 in, the motor. Only thirteen years ago that ratio Avas simply prohibi- 

 tory. Any competent mechanical engineer who considered the matter 

 could have no difficulty in concluding that it was then practically 

 impossible to make a motor on any large and safe working scale which 

 would lift its own weight, much less the weight of a heavy i)assenger- 

 carrying machine and passengers as well. Since that date a large 

 progress has been achieved, and motors can now be made which, for 

 the same weight, will give a greatly increased power. One of the latest 



