] 010 Summary and Conclusions 



caution, considering the low maximum pressure to be undergone and 

 my practice in enduring it. 



I next sent down with more precaution, successively, seven miners, 

 Sardinians by birth, who ordinarily worked at extracting lead ore. 

 Their constitutions were rather weak. They had been exposed for 

 several years to swamp fevers prevalent in the country all summer. 

 These men had a poor diet, eating vegetables and fruits almost ex- 

 clusively; they slept in the open air six months out of the year. They 

 were in general indolent and did a poor day's work. 



These details will perhaps explain why they were all seized by 

 more or less abundant nosebleed after having endured four to five 

 minutes, some of them ten, an atmospheric pressure corresponding 

 to 9 meters of water, the total depth of the basin into which they 

 descended. The fact is that without exception they ascended with 

 blood issuing from the nose and in some of them, from the ears. 



In general, symptoms of this sort appear only at great depths, 35 

 or 40 meters, especially when the decompression is too rapid. 



Observation XVI. Beginning of asphyxia in a closed vessel under 

 three meters of water. I descended equipped with an apparatus into 

 a little circular basin 3 meters deep and 4 meters in diameter. The 

 water was very muddy, and in spite of the shallowness, vision was 

 almost completely obscured; it was impossible to distinguish any- 

 thing on the outside. Inexperienced helpers managed the air com- 

 pression apparatus. 



I had lost my bearings during my first steps on the bottom of 

 the basin and the signal cord, which was not secured on the outside, 

 could not help me find the spot where the ladder was which would 

 have permitted me to return. And under these circumstances air 

 suddenly failed me. At least I could use only a reserve provided in 

 the receiver which enclosed me. The total capacity of this reserve 

 of pure air was about 30 liters. Taking on the average 12 inspira- 

 tions of 75 centiliters per minute, after three minutes I began to 

 breathe an air that had already been breathed. To escape immediate 

 asphyxia, at the beginning I took care to separate from the apparatus 

 the lead weights which held me on the bottom, so that I could rise 

 to the surface. I succeeded easily in detaching one of these weights, 

 but the second was still held by a cord when all effort became im- 

 possible to me. I was perspiring abundantly. I had a sensation of 

 intense heat in my head which diminished towards my lower limbs, 

 which seemed cold; my feet prickled. 



I breathed very quickly and as if I had not been able to empty 

 my lungs by expiration. This peculiar impression of a conviction 

 that I could not expel the air in my lungs was very distinct. I note 

 it very particularly. Far from suffering from not being able to breathe, 

 I had a feeling that I could not exhale. The sensation appeared to 

 me about like what one would experience if one were buried up to 

 the neck and one's head were in a steam bath at high temperature. 



My ears rang and luminous circles appeared before my eyes. 



Air returned to me then, and the symptoms disappeared. I re- 

 covered in a few minutes, fastened on my weights, and staid ten min- 

 utes longer in the water so as not to ascend until I was quite normal. 



