Mystery of 
Flight. 
(‘93) 
THE BIRD WORLD. 
Mystery of Flight. 
What bearing, if any, does the 
mysterious principal of bird-flight have 
upon the problem of aerial navigation? 
Will the solution of that problem be 
found when the mystery of bird-flight is 
a mystery no longer? Both questions 
are discussed in a most interesting 
fashion by Mr. Harold Bolce, in a con¬ 
temporary, whose investigations into the 
physics of bird-flight have attracted the 
respectful attention of aeronauts 
throughout the world:—“ The one fact 
in regard to the flight of birds that has 
struggled for recognition is that these 
creatures are not buoyant. Alive they 
weigh practically the same as when dead. 
Shot in mid-air they fall like meteors. 
A bird is not a balloon. This funda¬ 
mental principle, that all winged 
creatures are heavier than the bulk of 
the air they displace has vast significance 
for aeronauts. Reasoning from the 
Nubian Vulture, which, weighing from 
seventeen to twenty-two pounds, moves 
majestically in its course undisturbed by 
tempests, advanced students of aerial 
navigation predict that an aeroplane 
weighing ten times as much as a vulture 
will ultimately move through the air with 
even greater security and steadiness.” 
Many Theories. 
Many theories have been advanced, 
and many explanations offered to ex¬ 
plain the secret of the bird’s flight. 
There is, for example, the “ hollow-bone 
and air-sac ” theory, which maintains 
that as the temperature of birds is higher 
than that of any other creature, this net¬ 
work of air-chambers, becoming filled 
with air warmer than the surrounding 
atmosphere, enables the bird to rise. 
Another explanation of bird-flight that 
occurs to the casual observer, is that 
winged creatures fly by flapping their 
wings. But all birds do not do so. In 
fact, the birds that fly the best and most 
fearlessly can proceed for hours, and 
sometimes for a whole day, without 
making the slightest perceptible move¬ 
ment of their wings. 
Contradictory Theories. 
Perhaps the most common theory in 
explanation of flight on motionless wings 
is that the birds take advantage of air 
currents. But how does this work out 
in actual practice ? Whilst it is perfectly 
true that the Albatross needs an unfailing 
breeze to enable it to sail, it is equally 
certain that the Man-o’-war Bird can rise 
in the calm, and can sail without move¬ 
ment of its wings:—“ This theory of 
necessary air-currents may have been as 
serious a hindrance to the progress of 
aeronautics as has been the fallacy that, 
in order to sail, a ship must be lighter 
than air. But the fact that there is 
among the myriad of bird species a 
number that wing their way without 
effort in either calm or storm, some of 
them sailing on motionless pinions, 
furnishes the hope and possibility that 
man may also become absolute master 
of the air. The air-ship may some time 
be as indifferent to wind as is an ocean 
liner.” 
Running or Teaping. 
Lastly, there is the theory that the 
secret of flight lies in preliminary 
momentum gained by running or leap¬ 
ing from a height. Here, again, how¬ 
ever, says Mr. Bolce—“We are faced 
with a mass of contradictions, though 
the law of initial energy has been utilised 
to great advantage in experiments with 
aeroplanes. But that all airships of the 
future must invoke this law and be shot 
out of aerial harbours on head-long 
voyages is by no means evident. 
It is likely that the bird’s superb ease 
and grace in the air are due to its ability 
to maintain absolute balance, and for 
this purpose the bird is provided with a 
most sensitive equipment, made up of 
nerves and mysterious air-ducts; many 
of the wing feathers, perhaps, acting as 
sentinels, warning instantly of the 
slightest approach of shifting currents.” 
If this really be the case, it is not easy 
to see how any mere human contrivance 
for aerial flight can ever be more than 
partially successful. 
