330 



NATURE 



[May 4, i 9 i 1 



TRAVELLING AT HIGH SPEEDS ON THE 

 SURFACE OF THE EARTH AMD ABOVE I'l 



" The Spirii of the lim« tball le»cb ro« Speed."— A'/»v/**"' 



'PHERE are ft-w things so important to man from a 

 ^ material puint of view us tliv )x>wit uf locomotion ; 

 seeing, thcnfun-, that in this resp<-<t he iit far leM well 

 endowed by nature than many, if not most, living crea- 

 tures, it is no wonder that he ha$ striven from the earliest 

 times to overcome his inferiority by means of mechanical 

 devices. 'Ihe marvellous results of tht>,(; unceasing 

 attempts which to-tlay w*- «njoy, or, as som»- people would 

 prefer to say, " take advantage of," are accepted by most 

 of us as a mere matter of course, and we are further apt 

 to assume that the progress which has been so marl«-d 

 during the last century, and particularly in recent years, will 

 continue indefinitely. Now, quite apart from mere locomo- 

 tion, the question of speed is one of great scientific interest, 

 and, more than this, it is the real test of the power of 

 locomotion. This is not a mere accident, but has its root 

 in soniething far deeper. The desire for speed is a quality 

 inh«?rent in man, and is doubtless a primordial instinct, the 

 reason for which we see in all other animals, being 

 derived from prehistoric ages, when speed was a necessity 

 of life to enable the weak to escape from the strong and 

 to enable the strong to prey upon the weak, and man 

 dep<'nded, just as the animals in prehistoric times, for his 

 life on his Heetness and speed of motion. 



From what few and somewhat un- 

 certain records we have of the achiev<- 

 ments of man in running in the ancient 

 sports, it does not seem , there is very 

 much difference between his powers 

 then and in modern times. .As to 

 modern times, we find that for the 

 short distance of too yards, and for the 

 longer distance of a mile, the records 

 of twenty-live years ago still stand, not- 

 withstanding the strenuous efforts made 

 to improve upon them on many scores 

 of occasions each subsequent year. 

 Thus we have for the former the record 

 of E. Donnovan in i886, 2 13 miles an 

 hour, and in the same year the record 

 of W. G. George for the mile, 142 

 miles an" hour, which have never been 

 beaten ; while for one distance, that of 

 200 yards, the record of Se wards in 

 1847, or sixty-four years ago, still 

 stands. In fact, a study of all the 

 records of twenty-five distances shows 

 that several of them remain unbroken 

 after comparatively long periods, viz. 

 from a quarter to half a century. 



Thus, so far as his own unaided 

 powers of locomotion are concerned, 

 man may be considered, for all practical 

 purposes, to have reached long ago the limit of speed 

 possibility. From earliest times, however, he has brought 

 the muscular effort of other animals into his service, and 

 has devoted his intellect towards improving their speed 

 for his own uses. You will see graphically recorded in 



■— with a body moving alonn n livel plain, i.t. ^i n 

 lit distance from the t:.< rr, this • :: 



is nil. To understand i w'- mu«". 



the nature of animal Icjcomolion. iU 

 earth is rough, slidinf; along it being o»> <•: 



question; nature ha- 

 ment as follows :— -01 

 ground, another |>;irt ,,,..., ... 



raised clear of ili- ,;•'!, to rest in turn upi.: 

 and serve in turn ..-^ 1 support, so that thc 

 may b«: raised and advan«'.*d to a fresh position, lu ». 

 and other animals the feet form the points of support (< 

 this process ; but the same method of kKotnotion 

 «mploved by creatures without feet, which have to *V.i 

 or glidf, such as snakes or worms. 



Ihis process, whetht-r with animals or reptiles, as you 

 will see, involves in the raising of tl»e body an expenditure 

 of work which is not recovered, and further an »-xpf-ndi- 

 ture of work in stopping and starting some portion of 

 the body in its movements. My assistant now walks in 

 front of the blackboard holding a piece of chalk level 

 with his head, and you will see the r-- "-■ ■"'• 'Ming 

 motion. I have prepared a wooden nKxl h»- 



action of his legs, and you will see that • ng 



equal to his in length, produce almost exactly il»e same 

 curve underneath, so that you have a complete explanation 

 of this movement, viz. the rotation of the hip about the 

 ankle as a pivot. There is a third case of loss, namely. 



» 







>bSJ 



YEAR 

 Fig. I. — Derby Winners for 55 years. 



the energy involved in swinging the legs. .About thirty 

 years ago the distinguished French professor, Marey, 

 actually investigated the loss involved from each of these 

 three causes, and I have on the wall a diagram in which 



you will see all three given graphically. The number! 

 Fig. 1 the speeds of all the Derby winners from the year j of steps per minute, you will notice, increases until a 

 1856, i.e. for more than half a century. The average j pace is reached when it becomes painful to walk faster. 





speed, which may be taken as .somewhere above 30 miles 

 an hour, has doubtless slightly increased, but it will be 

 seen from the dotted line which has been drawn at the 

 top of the maximum speeds what comparatively little 

 increase has been obtained for an expenditure of the many 

 millions represented directly and indirectly in the training 

 and breeding of these horses, and it may be reasonably 

 assumed that here again the limit has been reached for 

 the fleetest animal, by the aid of which man can increase 

 his speed of locomotion by using muscular power other 

 than his own. 



XVhat, then, are the physical reasons for this limitation? 

 It is not due to the chief cause, which we shall see later 

 puts a practical limit to very high speeds in mechanical 

 locomotion, namely, the resistance of the atmosphere. 

 Neither is it due to the effective work done in movement, 



1 OUcourse delivered at the Royal Institution on Friday, March 31, by 

 Prof. H. S. HeleShaw. F.R.S. 



and you will also notice from the diagram that at about 

 ninety steps per minute the gait changes to a run, that 

 is to say, a springing action takes place, the hind foot 

 leaving the ground before the front is put down upon it. 



I have another diagram showing how the l«»ngth of 

 stride at first increases with the pace, and afterwards 

 begins to fall off before the walking breaks into a run. 

 The reason whj' a man or an animal changes his pace 

 at this point is obvious, and it is because a faster speed 

 is possible with a less effort. .As the speed of running is 

 increased the total effort becomes greater, but the three 

 elements shown on the diagram are differently divided : 

 the rise and fall element is less, but the work done in 

 swinging the legs is more, while the chief element, in 

 the muscular effort expended, is the loss of energy in- 

 volved in stopping and starting as each spring reaches a 

 maximum. Time does not permit me to pursue this 

 interesting subject further except to point out that exactly 



NO. 2166, VOL. 86] 



