TRAVELING AT HIGH SPEEDS—HELE-SHAW. 633 
26 miles 385 yards in (to be exact) 2 hours 55 minutes 18% seconds, or 
at the rate of 9 miles per hour, which, you see, fits very well on our 
curve. 
We may notice in passing that in walking fast and starting to run 
the arms swing in time with the opposite leg, as in the modern picture 
on the diagram exhibited. In the picture, however, copied on the 
same diagram from an ancient Greek vase, although the attitude of 
the legs is the same, it might appear at first sight as if the arms were 
swinging in the contrary way. Asamatterof fact, a closer examination 
shows that in all the figures on the vase the arms are in the same posi- 
tion, although the legs are in different phases. This seems to indicate 
that the arms of a Greek runner were held in a fixed position, as shown, 
and from the position of the hands, with the evident intention of cut- 
ting the wind. If this is true, it indicates that even then it was clearly 
recognized that if there was any effect of the wind it was just as 
important behind as in front, a matter I shall have to allude to 
hereafter. 
What man can do by his muscular effort in the water is shown by 
the small curve in the corner. The greatest distance shown (fig. 2) is 
about 21 miles by Capt. Webb at about 1 mile per hour, although for 
a short distance it will be seen that a man can swim at about 4 miles 
per hour. I do not put in flying, because man has not yet flown by 
_his own muscular effort, and flying men to-day are using engines of 
. from 20 to 100 horsepower, i.e., from 200 to 1,000 man power. Gliding 
per se is no more than falling through the air (more or less) gradually, 
as in a parachute. 
Before proceeding to see what man has done to increase his powers 
of purely muscular locomotion by means of mechanical devices we will 
study the details of locomotion in the other animals. We are able to 
do this by the method of Mr. Muybridge, since developed in the nven- 
tion of the cinematograph, and which was explained by Mr. Muy- 
bridge for the first time in this country about 30 years ago in a lecture 
in this hall. 
Take first the galloping horse. The lantern diagram shows clearly 
the various phases in the action of a horse, and shows how the animal 
is not only able to attain its high speed by its length of stride, but by 
doing what man can not do to the same extent—drawing up its body 
and in springing forward, using alternately its fore and hind feet, so as 
to get a stride which no two-footed creature could attain on the level 
ground. I may point out that the kangaroo, though using only two 
legs, makes effective use of its tail in the spring. The horse springs 
clear of the ground off its forefeet, only you will notice that it uses 
both its fore and hind legs as the spokes of a wheel on which it rolls 
when walking (exactly as man does), though it rolls and swings 
alternately in galloping. The same kind of diagram could be con- 
