282 Historical 



decrease of pressure and in workmen who are being decompressed 

 when they leave the caissons of bridge piers. In his opinion, as 

 we shall see at the proper time, hemorrhages are due partly to 

 the escape in the vessels of the carbonic acid of the blood, which 

 has been stored up there in exaggerated proportions during the 

 compression. 



Decompression by ascent would produce the same effect; and if 

 hemorrhages have been noted particularly in mountain climbers, 

 the theory which he suggests may explain the difference in these 

 effects: 



The man who rises in an aerostat performs practically no work 

 except that required by the respiratory movements. The man who 

 climbs a lofty mountain, on the contrary, makes a considerable muscu- 

 lar expenditure and must load his blood with carbonic acid. Is it not, 

 moreover, to this accumulation of carbonic acid in the blood that 

 certain authors attribute this peculiar dizzy state called mountain 

 sickness? (P. 102.) 



Errors are hardy. It is strange to note that in spite of the 

 authoritative answer made by M. Jourdanet to the theory of the 

 Weber brothers, it continues to be taught almost universally. 

 M. Beclard, 120 in the last edition of a book which should be in 

 the hands of all students, says, in fact: 



When man rises in the air, climbing very high mountains on 

 foot, as the rarefaction of the air increases, he experiences a very 

 peculiar feeling. It seems to him that his limbs are heavier; the 

 lower limbs especially soon become the seat of a fatigue which urges 

 him to rest. Hardly has he stopped an instant when this fatigue 

 disappears to reappear after a short time; and so on. This is what 

 happens; the atmospheric pressure is no longer sufficient by itself to 

 keep the head of the femur firmly against the cotyloid cavity, and 

 thus counterbalance the weight of the lower limb, and muscular effort 

 must keep the limb in its articular relations. This unusual muscular 

 effort is promptly followed by need of rest for the muscles .... 



This effect is felt even when the differences in pressure of the 

 barometric column are not very great. When the barometer falls, 

 since the muscles have to move heavier organs, we say that the 

 weather is heavy, although in reality the pressure exerted upon the 

 surface of the body by the atmospheric column is less. Likewise, 

 when the barometer rises, movements are made more easily. (P. 

 697.) 



As to the symptoms of decompression other than heaviness of 

 the limbs, M. Beclard attributes no importance to them when the 

 transitions are made rather slowly: 



At Potosi (4000 meters), at Deba (5000 meters) .... the functions 

 of metabolism, respiration, and circulation of the mountain dwellers 



