FLIGHT AND FLYING MACHINES. 495 
seems quite likely that we might find it very useful in experimenting 
on flying machines, to try starting them over the surface of water. 
Another animal, which is “ learning to fly,” but has not yet lcarnt, is 
the flying squirrel; this has developed a large sort of wing surface 
which helps to sustain it in leaping from bough to bough, and its 
agility saves it from any danger of accident. 
The next point that I propose, consider, and to illustrate by slides 
is the flight of birds. M. Marey, as many of you are probably aware, 
has made a considerable number of experiments on the action of bird’s 
wings. One of his apparatus, which he attached to a pigeon, is a sort 
of recording apparatus. You might exclaim “ poor pigeon,” but I 
believe the pigeon does not mind the apparatus much; M. Marey used 
a pigeon which has got accustomed to it. Various recorders were 
attached to different parts of the wings, in order to ascertain the 
variations in their position and also in their inclination during each 
stroke. In this way M. Marey constructed a diagram showing the 
results of these experiments. ‘This diagram shows the path of the tip 
of the wing and the various changes in the inclination of the wing 
during a complete stroke. You will see that the motion is not really 
an up-and-down action, but the tips of the wing travels in a sort of 
oval, and you will also see the varying inclinations of the wing surface 
which enable it to perform useful work in driving the bird forward and 
supporting its weight during the whole of the stroke. There is a 
mechanism that produces somewhat similar motion in the feathering 
paddle or paddle steamer; but whereas the paddle only requires to be 
made to “feather” during a small portion of each rotation in order to 
keep the blade perpendicular to the water during its immersion, this 
bird has to “ feather”? during the whole stroke, as the inclination of 
the wing varies at every point of the path. It is obvious that this 
action would be very difficult to imitate by means of any single 
machinery, and for this and other reasons the screw propeller is a much 
more convenient mechanism for the purpose of experiments on artificial 
flight. M. Pénaud has, however, constructed a bird with flapping 
wings, which do not move in an oval curve, but flap up and down on 
hinges. These wings are made of silk, which makes them flexible. I 
think you will see, when I set this model off, that it will rise in the air; 
it does not fly particularly well, but I hope to show you some that fly 
better. The present model only flies a short way and then falls; but 
a much larger one that M. Pénaud made flew a considerable distance, 
alternately rising and falling. 
I now propose to say a little about the photographic method of 
observing the flight of birds, which has also been developed greatly by 
M. Marey. Muybridge, you know, used a number of cameras for 
taking series of instantaneous photographs of moving objects, but 
while this plan answered very well for a galloping horse which had to 
go in a known direction, it would not be suited for taking photographs 
of objects whose direction of motion was uncertain, as in the case of 
birds. Accordingly, M. Marey found that for photographing birds in 
mid air a kind of photographic gun was the best apparatus. ‘This gun 
had a revolving plate which makes a number of successive exposures, 
