INSECT OR REACTIVE-PASSIVE LOCOMOTION. 67 
lip of a flower becaufe the winds were not blowing: and 
no wafp ever gathered lefs clay for his neft, or flopped a 
minute’s work for want of winds to fly on. Wind or no 
wind in the atmofphere, the wings of the little bufy bee, 
and wafp, and fly make neither one beat lefs nor more; 
for the locomotion of all is due to the impulfon of the 
air-preflures created by the fan-blowing adtion of their 
wings. 
Let us now conflder the philofophy of the fly that 
flood ftill in the air. The little fea-gull that I have 
defcribed as travelling with our fleamer by a fort of paf- 
flve locomotion—it fhould be obferved—invariably kept 
its pofltion juft above the fhip, not moving one inch for¬ 
ward or backward. With refpedt to the fhip, it flood as 
perfedtly ftill in the air as the little golden-green fly flood 
in the barn-yard. 
Now then, here we have two faEls. Let this be noted. 
In the cafe of the bird, the ftanding-ftill performance is 
clearly traceable to the force of the atmofpheric winds in 
the firmament, winds having their origin outfide of, and 
independent of, the bird. In the cafe of the fly (when I 
faw it), there were no winds in the atmofphere . 
Now if we aflume atmofpheric conditions fubftantially 
alike in both cafes, and admit—as admit we mu ft—that the 
wind-preftures fupporting the fly in fpace are due to the 
play of its wings—the conclufion is irrefiftible that the fly, 
when ftanding ftill, is as really fuftained by a balance of 
