THE LANGLEY AERODROME. 209 



Some soaring- birds do this by an initial run upon the ground, and OA^en 

 under the most urgent pressure can not fl}^ without it. 



Take the following graphic description of the commencement of an 

 eagle's flight (the writer was in Egypt, and the "sandy soil" was that 

 of the banks of the Nile): 



An approach to within 80 yards aroused the king of birds from his apathy. He 

 partly opened his enormous wings, but stirs not yet from his station. On gaining a 

 few feet more he begins to imlk away with half-expanded, but motionless, wings. 

 Now for the -chance. Fire! A charge of No. 3 from eleven bore rattles audibly but 

 ineffectively upon his densely feathered body; his walk increases to a run, he gathers 

 speed with his slowly waving wings, and eventually leaves the ground. Rising at a 

 gradual inclination, he mounts aloft and sails majestically away to his place of 

 refuge in the Libyan range, distant at least 5 miles from where he rose. Some frag- 

 ments of feathers denoted the spot where the shot had struck him. The marks of 

 his claws were traceable in the sandy soil, as, at first with firm and decided digs, he 

 forced his way; but as he lightened his body and increased his speed with the aid of his 

 wings, the imprints of his talons gradually merged into long scratches. The meas- 

 ured distance from the point where these vanished to the place where he had stood 

 proved that with all the stimulus that the shot must have given to his exertions he 

 had been compelled to run full 20 yards before he could raise himself from the earth. 



We have not all had a chance to see this striking illustration of the 

 necessity of getting up a preliminary speed before soaring, but many 

 of us have disturbed wild ducks on the water and noticed them run 

 along it, flapping their wings for some distance to get velocit}^ before 

 they can fly, and the necessity of the initial velocit}" is at least as great 

 with our flying machine as it is with a bird. 



To get up this preliminary speed many plans were proposed, one of 

 which was to put the aerodrome on the deck of a steamboat, and go 

 faster and faster until the head wind lifted it oft' the deck. This 

 sounds reasonable, but is absoluteh^ impracticable, for when the aero- 

 drome is set up anywhere in the open airw^etind that the very slightest 

 wind will turn it over, unless it is firmly held. The whole nmst be in 

 motion, but in motion from something to which it is held till that criti- 

 cal instant when it is set free as it springs into the air. 



The house boat was fitted with an apparatus for launching the aero- 

 drome with a certain initial velocitv, and was (in 1893) taken down the 

 river and moored in the stretch of quiet water I have mentioned — the 

 general features of the place being indicated on the accompanying 

 map, page 21.5 — and it was here that the first trials at launching were 

 made, under the difliculties to which I have alluded. 



Perhaps the reader will take patience to hear an abstract of a part 

 of the diary of these trials, which commenced with a small aerodrome 

 which had finally been built to weigh only about 10 pounds, which had 

 an engine of not quite one-half horsepower, and which could lift much 

 more than was theoretically necessary to enable it to fly. The exact 

 construction of this earh^ aerodrome is unimportant, as it was replaced 



