6o 
BIRD-FLYING. 
There was a time when inventors, or Tome of them 
at leaft, thought it neceffary to exactly imitate Nature 
in order to follow her, and with this view condemned 
wheels and argued for legs and feet inftead, not per¬ 
ceiving that the fpokes of the wheel are the legs, and 
the periphery the feet: the difference between the 
methods being that in one the fulcrum of fupport and 
locomotion is intermittent and in the other continuous. 
In the fame way, mankind have imitated Nature and 
conftrucfted wings —wings ££ to beat the air as a bird 
when flying.” And, where they have attempted fome- 
thing different, it has been a device poffefling no wing- 
fundtion whatever, a c£ helice ” or fcrew; the effetft of 
which, I admit, is bird-flying, but of the projetlile 
locomotion kind, far better, certainly, and more fenflble, 
than ££ aero-planes ” or any flat planes, and nearer to 
dragon-fly locomotion, for it introduces fmall furfaces 
and high velocities in place of extended furfaces with 
relatively flow movements. In this view it is an approach 
in the right direction, and the refults obtained by Nadar 
and Landelle at one time feemed quite encouraging. In 
my opinion they would actually have fucceeded had they 
been fortunate in the poffeflion of a true theory, for they 
would then have made a fanning-wheel inftead of a 
helice. 
With regard to the helice or fcrew, I fhall have 
fomething to fay in the Appendix. In this place I content 
