May 4, 191 1] 



NATURE 



i3i 



similar causes operate in the natural locomotion of other 

 animals which move on legs. 



We therefore now know that the limit of speed is con- 

 trolled by two factors : — 



(i) Physical endurance, owing to the expenditure of 

 work occurring at an increasing rate as the speed is 

 increased. 



(2) The physical impossibility of giving a reciprocating 

 movement to the legs quicker than a certain limited period 

 of time. 



I have prepared a chart, Fig. 2, which shows the maxi- 

 mum recorded velocities of man's progression in walking 

 and running. The speeds are set up as vertical ordinates, 

 and the abscissae represent the distances over which the 

 respective speeds were maintained. It will be seen 

 that the maximum speed of walking is about 9 miles 

 an hour for a short distance, but when the long distance 

 of 100 miles is covered, the quickest rate recorded falls 



20 



30 



60 



70 



40. SO 



MILCS 

 Fig. 2. — Speed Records for Hum.-xn Muscular Effort. 



to 5i miles an hour. For running, the quickest speed 

 which I have mentioned, viz. 21J miles an hour for 100 

 yards, falls to yi miles an hour as the average speed for 

 a distance of 100 miles. 



We do not know the speed of the original historical run 

 from Marathon to Athens, but we do know that Dorando 

 ran the modern Marathon from Windsor Castle to the 

 Stadium at Shepherd's Bush, a distance of 26 miles 385 

 yards in {to be exact) 2h. 55m. 18 2-55., 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 start- 

 ing to run the arms swing in time with the opposite leg, 

 in the modern picture on the diagram exhibited. In 

 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 position, although the legs 

 are in different phasps. This seems to indicate that the 

 arms of a Greek runner were held in a fi.xed position as 

 shown, and, from the {K>sition of the hands, with thf 



NO. 2166, VOL. 86] 



evident intention of cutting the wind. If this is true, it 

 indicates that even then it was clearly recognised 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 Captain Webb 

 at about i 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 \et 

 flown by his own muscular effort, and flying men to-day 

 are using engines of from 20 horse-power to 100 horse- 

 power, i.e. from 200 to 1000 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. Muy- 



' bridge, since developed in the invention 



of the kinematograph, and which was 



'explained by Mr. Muybridge for the 



first time in this country about thirty 



'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 

 cannot do to the same extent — draw- 

 ing up its body and in springing for- 

 ward, 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 springs 

 alternately in galloping. The same 

 kind of diagram could be constructed 

 for the effort exerted at different speeds 

 by the horse, as has been produced by 

 Marey for the man, only the distribu- 

 tion of energy would probably be very 

 different. 



Turning next to other animals, it is 

 interesting to observe that a greyhound 

 gets its high speed in proportion to its 

 size owing to the great flexibility of its 

 long body, which enables it to draw its 

 hind legs forward each time for the 

 next bound, and also bound forward 

 both from its fore and hind legs. The other animals 

 in galloping have each the same general kind of move- 

 ment, although the deer, ' curiously enough, only 

 bounds from its hind legs, and differs in this respect 

 from the horse ; and also it will be noticed the want 

 of flexibility in the body of an animal may be one of 

 the causes of its relatively slow speed. But whether 

 it be man, horse, d(^, or any other animal, the same 

 characteristic is found, namely, that locomotion, apart 

 from the bounding action, takes place by a sort of rolling 

 action on the ground. The idea which had persisted 

 since the delineation of horses in Assyrian and Egyptian 

 pictures, that both the fore or both the hind legs are 

 put on the ground simultaneously, is thus exploded. .As 

 Mr. Muybridge truly said : " When during a gallop, the 

 fore and hind legs are severally and consecutively thrust 

 forwards and backwards to their fullest extent, their com- 

 parative inaction may create in the mind of the careless 

 observer rm impression of indistinct outlines ; these suc- 

 cessive appearances were probably combined by the earliest 

 sculptors and painters, and with grotesque exaggeration 

 adopted as the solitary position to illustrate great spi'ed." 

 As a matter of fact, each leg in turn, as it rests on the 



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