INDUSTRIAL LABOUR 



447 



Taylor's system has gained ground in industry owing to the 

 undoubted value of its practical applications. In effect he put 

 into practice the theoretical conclusions which had already been 

 set forth by Chauveau, although it is not known whether he was 

 at first acquainted with that scientist's work. This application 

 was, however, incomplete, inasmuch as the important question of 

 the degree of fatigue was not dealt with by Taylor. 



338. The Expenditure of Energy in Speaking. A man expends 

 muscular energy in speaking as well as in lifting a weight. The 

 work done in the production of speech is complex in its nature. 

 It comprises phonution in the strict meaning of the term which 

 is the emission of a volume of air varying according to the speed 

 of talking and the intensity of the sound. If air of volume V is 

 inspired or expired under a pressure H, the- work done in these 

 respiratory movements, T = V X H. 



The pressure H should be measured in the treachea, or wind-pipe, 



of the subject by means of a 

 tube joined to a manometer 



Tract* es^^.^ 

 ' artery 



(vide fig. 307). The volume 

 V is measured by a spirometer 

 at the temperature of the 

 lungs and at atmospheric 

 pressure. 



Cagniard-Latour ( l ) was the 

 first to make an observation 

 of this kind, on a subject 32 

 years of age, whose larynx 

 was, as the result of an acci- 

 dent, perforated by a hole of 

 8 cm. diameter. The mano- 

 meter indicated a positive 

 pressure of 4 cm. of water in 

 expiration and a negative 

 pressure of 5 or 6 cm. in 

 inspiration, or an average 



respiratory pressure of about 5 cm. An adult displaces per 

 hour a volume of air of about 500 litres. Hence the work done 

 T = 500 X -05 X 2 = 50 kilogram met res. " We see, there- 

 fore," says Caigniard-Latour, " that the efforts exerted in the 

 motor insufflation of the vibrations of the larynx are not so small 

 as might have been anticipated in view of the apparently effort- 

 less manner in which the voice is employed under ordinary con- 

 ditions/' 



Diagram of lungs and bronicealtubes. 



Cagniard-Latour (Comptes Rendus Sciences, vol. iv., page 201, 1837. 



