12 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



every point with regard to its " economy " is completely 

 ascertainable and expressible in absolute units. 



Wishing to develop this view I turned my attention to 

 the expenses of " walking " as recorded by different observers, 

 but mainly, since most suitable for the purpose, to a series of 

 data collected by Douglas and Haldane as to the expense 

 incurred by Douglas when walking " on the grass at Oxford " 

 at different rates of progression. Neglecting the external work 

 performed in this process, and treating the whole expense as 

 " cost of movement " I found that the expenses could be 

 expressed in a formula similar to the one which had served to 

 unite the expenses of cycling movement. The similarity is 

 such as to leave little doubt that the two series of accounts 

 are governed, in the main, by similar considerations and that 

 the " economy " of walking is as capable of complete and 

 exact statement as the " economy " of cycling. In this case 

 as in the other, there is clearly a certain intermediate economical 

 rate. In this case there is, however, more immediate hope of 

 discovering the significance of this particular rate, in fact, 

 there is very little doubt as to the order of this significance, 

 but the explanation of this point necessitates a brief statement 

 as to the process of walking. 



In the opinion of the brothers Weber, who exhaustively 

 studied the apparatus of walking, and the process so far as 

 the " technique " of their time allowed, the swinging limb in 

 walking behaves exactly as a pendulum, and the variations in 

 the process evident in different walkers depend upon differences 

 in this pendulum. Important amongst the data which they 

 collected on this subject are data showing the length of the 

 step in walking as dependent upon the speed. Consideration 

 of the process as a " pendular process " anticipates this 

 variation in length of step, which they actually observed in 

 a complete and thoroughly scientific fashion. Now, later 

 observers have brought forward certain important considera- 

 tions and further observations, some of which are hostile to 



