AERIAL NAVIGATION. 181 



ventured to add the motor and propeller. This, in the judgment of 

 the present writer, is the only course of training by which others ma}'^ 

 hope to accomplish success. It is a mistake to undertake too much at 

 once and to design and build a full-sized flying machine ab initio, for 

 the motor and propeller introduce complications which had best be 

 avoided until in the vicissitudes of the winds bird craft has been 

 learned with gravity as a motive power. 



Now that an initial success has been achieved with a flying machine, 

 we can discern some of the uses of such apparatus, and also some of 

 its limitations. It doubtless will require some time and a good deal of 

 experimenting, not devoid of danger, to develop the machine to prac- 

 tical utility. Its flrst application will probabl}' be military, ^^^e can 

 conceive how useful it might be in surveying a Held of battle, or in 

 patrolling mountains and jungles over which ordinary means of con- 

 veyance are difficult. In reaching otherwise inaccessible places, such 

 as clifi's, in convejdng messages, perhaps in carrying life lines to 

 wrecked vessels, the fl3'ing machine may prove preferable to existing 

 methods, and it ma}"" even carry mails in special cases, but the useful 

 loads carried will be very small. The machines will eventually be 

 fast, they will be used in sport, but they are not to he thought of as 

 commercial carriers. To say nothing of the danger, the sizes must 

 remain small and the passengers few, because the weight will, for the 

 same design, increase as the cube of the dimensions, while the sup- 

 porting surfaces will onl}^ increase as the square. It is true that when 

 higher speeds become safe it will require fewer square feet of surface 

 to carry a man, and that dimensions will actually decrease, but this 

 will not be enough to carry nuich greater extraneous loads, such as a 

 store of explosives or big guns to shoot them. The power required 

 will always be great, say something like one horsepower to every 

 hundred pounds of weight, and hence fuel can not be carried for long- 

 single journeys. The north pole and the interior of Sahara may pre- 

 serve their secrets a while longer. 



Upon the whole, navigable ])alloons and flying machines will con- 

 stitute a great mechanical triumph for man, but they will not mate- 

 rially upset existing conditions as has sometimes been predicted. 

 Their design and performance will doubtless be improved from time 

 to time, and they will probably develop new uses of their own which 

 have not vet been thought of. 



