THE LAWS OF ENERGETIC EXPENDITURE 173 



expenditure of 11-90 cu. cms. With greater weights, carried to a 

 height of 6 metres in 75 seconds, Laulanie, a pupil of Chauveau, 

 obtained the following results ( x ) : 

 Weight ......... 20 40 60 80 100 kgs. 



Expenditure per kilo- ) 2 



grammetre ...... f 3 32 2 ' 38 2-13 cu. cms. 



The minimum of expenditure is, in this kind of labour, with a 

 load of 80 kilogrammes, at a speed of 0-08 metres. From all 

 these experiments it is clear that there are certain weights and 

 speeds which give maximum economy. It is most noticeable 

 in the speed, not so much by the number of contractions and the 

 rapid succession of movements, as by the extended displacements. 

 In walking, for instance, small quick steps are less economical 

 than big strides. As has been already pointed out, frequent 

 starts and stops multiply the demand on the nervous system, 

 and should be avoided where possible. Chauveau demonstrated 

 this experimentally. He caused the flexions of the arm to 

 succeed each other in growing number, in the same proportion 

 as the displacement of the weight decreased at each contraction, 

 so that in the end the weight was carried at the same height all 

 the time. The effect of the multiplicity of the contractions is 

 shown in the expenditure : ( 2 ) 



Expenditure per kilogrammetre : 



cu. cms. cu. cms. cu. cms. cu. cms. 



Weight of 3 kilogrammes ... 8-10 8-80 10-10 10-70 

 6 ... 9-50 9-50 12-20 13-30 



The expenditure, therefore, under these conditions, clearly 

 increases. The combination of weight and speed which leads 

 to the minimum expenditure is also found in the work of hydraulic 

 motors, for instance. ( 3 ) 



118. Resistant Work. Chauveau undertook some experiments 

 on resistant ( 4 ) work corresponding to those on motive work. 

 The weight, instead of being lifted, descends. The variations of 

 D' and of V Ph were as follows : 



(!) Laulani6, Trait de Physiologie, 1905, p. 792. 



() A. Chauveau (Compt. Rend. Acad. Sc., 1904, vol. cxxxviii., p. 69 ; 

 cxxxix., p. 13). 



( 3 ) G. Weiss (Comptes Rendus Biologic, 1903, p. 426) ; A. Chauveau, 

 Rapport Scientifique. sur Trav. Entrepris en 1905 aumoyen des subventions 

 de la caisse des recherches scientifiques, Melun, 1906. 



(*) A. Chauveau (Compt. Rend. Acad. Sciences, 1904, vol. cxxxviii., p, 108). 



