TRAVELING AT HIGH SPEEDS — HELE-SHAW. 633 



26 miles 385 yards in (to be exact) 2 hours 55 minutes 18f 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. As a matter of 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 inven- 

 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- 



