248 THE HUMAN MOTOR 



182. Fatigue is the true source of the physiological troubles 

 which characterise this sickness. ( l ) It is produced quickly, in 

 consequence, perhaps, of the lowering of the tension of oxygen 

 and the rarefication of the atmosphere. It follows that man is 

 not capable of performing the same amount of mechanical work 

 at great heights as at normal elevations. In the Burlard mines, 

 at Sentein, at 2,600 metres, a walk of only 600 metres to reach the 

 galleries, produces breathlessness.( 2 ) 



Bayeux's experiment explains this fatigue. Bancroft ( 3 ) 

 also showed that the affinity of the haemoglobin of the blood for 

 oxygen diminishes with altitude at the same rate as the alkalinity 

 of the liquid, which latter is conducive to the fixation of the 

 oxygen. 



We may estimate that the diminution of power of workmen 

 living at a height of 2,500 metres is 15%, even when they come 

 from heights of 700 to 800 metres. The Caylloma mines. South 

 Peru, are at 4,500 to 4,900 metres above sea level, and the work 

 of smiths, carpenters, wood workers and mechanics is there 

 lowered by half. In practice, say Trefois and Fox, one must 

 admit that at great altitudes the dynamic equivalent of a work- 

 man is considerably lowered by the rarification of the air alone. 



Cold has also a share in this reduction of output. Leaving 

 out of account the exceptional cold ( 40) of the mines in Lap- 

 land, Siberia, Alaska and Greenland, one must reckon with the 

 abundant snow, which is found between 2,000 and 3,000 metres 

 altitude, and which attains a thickness of 8 to 10 metres in winter 

 (the mines of Pieos, in Spain ; of the Pyrenees in France ; of 

 Vallauria, in Italy, etc.). The best paid workmen refuse to work 

 in such regions ; the soldiers on the Alpine posts resist the climate 

 but feebly, and, in consequence, fill the hospitals. In fact, in 

 the temperate zone, a mine at an altitude of 5,000 metres would 

 be absolutely unworkable, even if it contained golden sovereigns 

 ready minted. 



Therefore cold, fatigue, lack of oxygenation of the blood, 

 and, perhaps, the fear of danger ( 4 ), produce altitude sickness. 



It is interesting to note that the power of internal combustion 

 engines decreases from 11% to 25% at altitudes ot 1,000 to 

 5,000 metres ( 168). 



() See an interesting article by Kronecker Nature du Mai des Montagnes 

 et un Cas rare de ce Mai, in Biologische Centralblatt (vol. xxxi., 1911). 



( 2 ) G. Trefois (Revue Univ. des Mines, July, 1910, p. 38, Liege). 



(*) Bancroft (Journal de Physiol., vol. xlii., p. 44, 1911. Proceedgs. Roy. 

 Soc. Land., 18th Jan., 1912)." 



( 4 ) D'Hombres Firmas (Comptes Rendus Sciences, vol. iii., p. 382, 1836). 



