322 ON AERIAL LOCOMOTION. 



down by cords or chains niuuiiig over pulleys in the panels b h, and 

 fastened to the end of a swiveling cross-yoke, sliding on the base-board. 

 By working this cross-piece with the feet, motion will be communicated 

 to the propellers, and by giving a longer stroke with one foot thau the 

 other a greater extent of motion will be given to the corresponding pro- 

 peller, thus enabling the machine to turn just as oars are worked in a 

 rowing-boat. The propellers act on the same principle as the wing of a 

 bird or bat; their ends being made of fabric, stretched by elastic ribs, 

 a simple waving motion up and down will give a strong forward impulse. 

 In order to stop, the legs are lowered beneath the base-board, and the 

 experimenter must run against the wind. 



An experiment recently made with this apparatus developed a cause 

 of failure. The angle required for producing the requisite supporting 

 power was found to be so small, that the crinoline steel would not keep 

 the front edges in tension. Some of them were borne downward and 

 more on one side thau the other, by the operation of the wind, and this 

 also produced a strong fluttering motion in the webs, destroying the 

 integrity of their plane surfaces, and fatal to their proper action. 



Another arrangement has since been constructed, having laths sewn 

 in both edges of the webs, which are kept permanently distended by 

 cross-stretchers. All these planes are hinged to a vertical central 

 board, so as to fold back when the bottom ties are released ; but the 

 system is much heavier than the former one, and no experiments of any 

 consequence have as yet been tried with it. 



It may be remarked that although a principle is here defined, yet 

 considerable difficulty is experienced in carrying the theory into prac- 

 tice. When the wind approaches to 15 or 20 miles per hour, the lifting 

 power of these arrangements is all that is requisite, and by additional 

 planes, can be increased to any extent ; but the capricious nature of the 

 ground-currents is a perpetual source of trouble. 



Great weight does not appear to be of much consequence, if carried 

 in the body ; but the aero-planes and their attachments seem as if they 

 were required to be very light, otherwise they are awkward to carry, 

 and impede the movements in running and making a start. In a 

 dead calm it is almost impracticable to get sufficient horizontal speed 

 by mere running alone to raise the weight of the body. Once off the 

 ground, the speed must be an increasing one, if continued by suitable 

 propellers. The small amount of experience as yet gained appears to 

 indicate that if the aero-planes could be raised in detail, like a super- 

 posed series of kites, they would first carry the w^eight of the machine 

 itself, and next relieve that of the body. 



Until the last few months no substantial attempt has been made to 

 construct a flying-machine in accordance with the principle involved 

 in this paper, which was written seven years ago. The author trusts 

 that he has contributed something towards the elucidation of a new 

 theory, and shown that the flight of a bird in its performance does not 



