REACTIVE LOCOMOTION. 
26 
number three is regarded by many as the a lucky number,” 
fo that we have the expreflion in common ufe, ic the third 
time is always fure to win.” I venture to hope that it 
may in this cafe prove true. 
The wind that oppofes the bird is alfo the power that 
floats it ; and the problem of locomotion in the air for all 
the creatures that fly in it is one of flotation primarily, 
from whatfoever fource or by whatfoever means the wind- 
preflures may be induced. 
The men of 1782 were quite right in regarding 
flotation as the pivot in the problem, wrong only in mif- 
taking fpecific^gravity-flotation for the method of Nature. 
And thofe who before and thofe who flnce 1782 have 
theorized and experimented to folve the problem of aerial 
navigation have failed becaufe their attention has been 
wholly fixed upon the machine or flying creature inftead 
of the atmofphere. It is not the machine or the flying 
creature we need to change, but the air . The atmofphere 
is too light to buoy us up. We mull change the fpecijic 
gravity of the air . 
The Montgolfiers and men of Franklin’s day attempted 
to folve the problem by changing the fpecific gravity of 
the machine or flying creature, with not a Angle analogue 
in Nature to juftify them, and later experimenters have 
dealt with the queftion as one of proje&iles. 
Birds fail or glide through the air by employing their 
weight as projedtile force. Birds are floated through the 
