ON THE SOURCE OF MUSCULAR POWER. 



255 



It is thus evident that the muscular power expended by these gen- 

 tlemen in the ascent of the Faulhorn could not be exclusively derived 

 from the oxidation, either of their muscles, or of other nitrogenous 

 constituents of their bodies, since the maximum of power capable of 

 being derived from this source even under very favourable assump- 

 tions is, in both cases, less than one-half of the work actually per- 

 formed. But the deficiency becomes much greater if we take into 

 consideration the fact, that the actual energy developed by the oxida- 

 tion or combustion cannot be wholly transformed into mechanical 

 work. In the best constructed steam-engine for instance, only -^ of 

 the actual energy developed by the burning fuel can be obtained in 

 the form of mechanical power ; and in the case of man, Helraholts 

 estimates that not more than |- of the actual energy developed in the 

 body can be made to appear as external work. The experiments of 

 Haidenhain, however, show that, under favourable circumstances, a 

 muscle may be made to yield in the shape of mechanical work as 

 much as one-half of the actual energy developed within it, the rc'- 

 mai'nder taking the form of heat. Taking then this highest estimate 

 of the proportion of mechanical work capable of being got out of 

 actual energy, it becomes necessar^?^ to multiply by 2 the above num- 

 bers representing the ascertainable work performed, in order to ex- 

 press the actual energy involved in the production of that work. 

 We then get the following comparison of the actual energy capable 

 of being developed by the amount of muscle consumed, with the ac^ 

 tual energy necesssary for th« performance of the work executed in 

 the ascent of the Faulhorn. 



Actual energy capable of being produced by 



Muscle metainorphosis 



Actual energy expended in work performed . 



Fick. 



Metrekilograms. 



68,fi90 

 819,2'!'4 



Wislicenus. 



Metrekilograms. 



68,376 

 868,574 



Thus, taking the average of the two experiments, it is evident that 

 ^earcely \th of the actual energy j-eqnired for the work performed 

 <ionld he ohtairved from the amount of muscle consumed. 



Similar though not quite so conclusive results were obtained from 

 experiments made on prisoners engaged in treadmill labour, on mili- 

 tary prisoners engaged in shot drill, and on Various kinds of labourers. 



Vol. XI. s 



