1166 The Problem of the Soaring Bird. [ December, 
been found to exist which calls for something better than guess- 
work in way of explanation. Taking the case of a ten-pound 
bird with tensely stretched and motionless wings, facing a breeze 
anywhere from two to one hundred miles per hour, and resting 
serenely over the same spot of earth, without effort and without 
fatigue, we find our habitual notions about the difficulty of keep- 
ing unsupported substances in the air at fault. We want a solu- 
tion of the matter from the standpoint of the mechanical engineer. 
We need not go into the domain of molecular physics for an- 
swers, but we wish the bird explained in the same way that a 
steam-engine is explained when we examine it as a machine 
doing work. To this end we may ask three questions, and satis- 
factory answers being found thereto, the phenomenon will be 
comprehended. 
I. From whence is derived the motive power to balance 
gravity ? 
. 2. From whence is derived the motive power to hold the bird 
against the wind ? 
3. How are these forces applied ? 
To explain a steam-engine in this same sense but two en 
tions demand answer. 
1, From whence comes the motive power to drive the piston? 
2. How is this force applied ? 
When we say that the force which moves the engine comes 
from the coal that is burning in the furnace, and is conducted 
through pipes by the medium of steam to a movable piston which 
it sets in motion, we have, in a general way, given an explanation 
to the activities there going on. When we say. that the grind- 
stone is operated by the force derived from the muscular organi- 
zation of the boy turning it, then its action is also explained 
It is in this way that an attempt will be made to explain a 
soaring bird. No objection is taken to the view that force cannot 
produce motion, held by some recent scientists. Granted that 
ee but motion can produce motion, and I am then only con- 
ce with the sequence of events; with having it understood 
l that the motion of the piston is not the cause of the burning 
al, nor that the grindstone turns the boy. 
I en the eee tornado struck the birds as above related, 
: iv Wes = on between bird and air were 
