206 THE LANGLEY AEEODROME. 



batteries, unci numerous other contrivances, but all in vain. The gas 

 engine promised to be best ultimately, but nothing save steam gave 

 any promise of immediate success in supporting a machine which would 

 teach these conditions of flight by actual trial, for all were too heavy, 

 weight being the great enemy. It was true also that the steam-driven 

 model could not be properly constructed until the principal conditions 

 of flight were learned, nor these be learned till the working model was 

 experimented with, so that it seemed that the inventor was shut up in 

 a sort of vicious circle. 



However, it was necessary to begin in some way, or give up at the 

 outset, and the construction began with a machine to be driven by a 

 steam engine, through the means of propeller wheels, somewhat like 

 the twin screws of a modern steamship, but placed amidships, not at 

 the stern. There were to be rigid and motionless wings, slightly 

 inclined, like the surface of a kite, and a construction was made on 

 this plan which gave, if much disappointment, a good deal of useful 

 experience. It was intended to make a machine that would weigh 20 

 or 25 pounds, constructed of steel tubes. The engines were made with 

 the best advice to be got (I am not an engineer) ; but while the boiler 

 was a good deal too heavy, it was still too small to get up steam for 

 the engines, which weighed about 4 pounds, and could have developed 

 a horsepower if there were steam enough. This machine, which was 

 to be moved by two propelling screws, was labored on for man}^ 

 months, with the result that the weight was constantly increased 

 beyond the estimate until, before it was done, the whole weighed over 

 40 pounds, and 3'et could only get steam for about a half horsepower, 

 which, after deductions for loss in transmission, would give not more 

 than half that again in actual thrust. It was clear that whatever pains 

 it had cost, it must be abandoned. 



This aerodrome could not then have flown; but having learned from 

 it the formidable difiiculty of making such a thing light enough, 

 another was constructed, which was made in the other extreme, with 

 two engines to be driven by compressed air, the whole weighing but 

 5 or 6 pounds. The power proved insufiicient. Then came another, 

 with engines to use carbonic-acid gas, which failed from a similar 

 cause. Then followed a small one to be run by steam, which gave 

 some promise of success, but when tried indoors it was found to lift 

 only about one-sixth of its own weight. In each of these the con- 

 struction of the whole was remodeled to get the greatest strength and 

 lightness combined, but though each was an improvement on its pre- 

 decessor, it seemed to become more and more doubtful whether it 

 could ever be made sufficiently light, and whether the desired end 

 could be reached at all. 



The chief obstacle proved to be not with the engines, which were 

 made surprisingly light after suflicient experiment. The great difli- 

 culty was to make a boiler of almost no weight which would give 



