EXPERIMENTS WITH HORIZONTAL WALKING. 139 



computing the increase on March 27, April 3, and 24, on which there 

 were no standing experiments. 



TOTAL INCREMENT IN HEAT-PRODTJCTION. 



The total increment in the heat-production above the standing 

 requirement is assumed to represent the energy cost of the transporta- 

 tion of the body- weight over a definite distance on the level as expressed 

 in horizontal kilogrammeters. As the amount of this total increment 

 naturally depends upon the speed of walking, the values in column h 

 are of but minor interest here, especially as theoretically no work is 

 done in this process and no efficiency value can be computed. It may 

 be noted, however, that for moderate rates of walking, i. e., 50 to 

 60 meters per minute (approximately 2 miles an hour), the total in- 

 crease for most of the subjects is a little less than double the standing 

 requirement, with W. K. an apparent exception. E. D. B. shows for 

 speeds of 95 to 100 meters per minute (approximately 4 miles an hour), 

 an increase of nearly three times his requirement when he was stand- 

 ing, while for a speed of 35 meters per minute the increase was about 

 the same as for the standing requirement, or, stated in another way, 

 when the walking was done at a rate of 35 meters per minute, only half 

 of the total energy expended was due to the act of walking. 



INCREMENT IN HEAT PER HORIZONTAL KILO GR AMMETER. 



The main point of interest in tables 29 to 33 is the increment in the 

 heat per horizontal kilogrammeter, as this shows the energy cost of 

 walking 1 horizontal meter. This is later used to represent the hori- 

 zontal component in the energy cost of grade walking. These values 

 are given in column i of the several tables. 



For A. J. 0., at a speed of approximately 63 meters per minute, the 

 walking was done at a cost of from 0.416 to 0.501 gram-calorie per 

 horizontal kilogrammeter, with an average value for the three days of 

 0.454 gram-calorie. (See table 29.) 



The data for H. R. R. show a range in the average values for cost 

 per horizontal kilogrammeter from 0.643 gram-calorie on the first day 

 to 0.574 gram-calorie on the last day. The first period of the first 

 day (March 20) was marked by the fact that the largest energy cost 

 for this subject was here found. As noted in the discussion of table 3, 

 the highest standing metabolism for this subject was also found on this 

 day. In spite of this high standing metabolism, the increase for the 

 horizontal walking is greater than on the subsequent days. On the last 

 two days of experimenting, H. R. R. seems to have walked at a less 

 cost per horizontal kilogrammeter, but the data are too limited for the 

 drawing of any conclusions as to the real betterment in this man's 

 ability to walk with a smaller energy outlay as the time progressed. 



T. H. H., walking at a rate varying between 63 and 68 meters per 

 minute, had an increase in the energy output per horizontal kilogram- 



