396 THE HUMAN MOTOR 



with fair accuracy, the production of work by man under normal 

 conditions. Coulomb, alone, at that time, and Bouguer f 1 ) and 

 S'Gravesande ( 2 ) at a later date, recognized the important in- 

 fluence of the speed of working, on the daily output. The others 

 paid no attention to this factor. 



In the nineteenth century the professors of pure mechanics 

 ceased to hold the field. Navier ( 3 ), Corioli, Dupin and Poncelet, 

 who did so much for the development of workshop machinery, 

 failed, through want of proper methods and apparatus, to solve 

 the problem of the human machine, although they fully appre- 

 ciated its importance and the value of the practical results 

 which might spring therefrom. ( 4 ) Whilst Dupin devoted his 

 lectures at the Conservatoire to this matter, Poncelet made it 

 his subject at Metz. The enthusiasm was quickly exhausted, 

 because there was really nothing with which to feed it. 



Since 1855, thanks to the work of Chauveau. the evaluation of 

 the expenditure of energy has been carried out by the applica- 

 tion of the science of energetics. It must not, however, be for- 

 gotten that Lavoisier was the first to formulate and apply the 

 principle of measuring the work done by the corresponding con- 

 sumption of oxygen. He remarked that by this method com- 

 parison could be made between forces which, at first sight, 

 appeared to have no inter-relation. Thus it was possible to 

 measure in ordinary physical units, the expenditure of energy 

 of the orator, the musician, the writer, the composer, or even the 

 philosopher immersed in thought. Such actions, generally con- 

 sidered as purely mental, have. then, their physical and material 

 elements, by virtue of which they can be compared with the 

 actions of manual labour. It is therefore not without fitness 

 that the French language includes, under the one word, " travail," 

 the work both of head and hand.( 5 ) 



The logical development of this far-reaching generalization was 

 due to the masterly work of Chaaveau alone, as far as France 

 was concerned. In America Atwater and his school followed on 

 the same lines. Much data of value in the scientific study of 

 labour was, however, collected in other countries, by Mosso and 

 Treves in Italy, by Zuntz ( 6 ) du Bois-Reymond, and A. Loewy, 

 and their numerous followers in Germany. 



f 1 ) P. Bouguer, Trait & du Navire, p. 109, 1746. 



( 2 ) S'Gravesande, Phy sices Elem. Math., I., No. 1856. 



( 8 ) Navier, Architecture Hydr., Belidor, 1819, notes, p. 382. 



(*) See especially the Inaugural Lecture of C. Dupin at the Conservatoire 

 Nationale des Arts et Metiers (Discourse of 25th Jan., 1829). 



( 6 ) Lavoisier (Euvres Completes ii. p. 688 (Edition Officielle). 



(*) Zunt/. and Schumburg Studien zu einer Physiol. des Marsches Berlin, 

 1901. 



