438 EXPERI3IENTS BY M. PAUL BERT. appendix. 



of that which would be experienced at the top of Mount Everest, and about 

 one tenth of atmospheric pressure at the level of the sea. 



These experiments upon animals were followed by others upon himself. 

 M. Bert says (p. 749) :— 



'•Je ne pouvais evidemment me borner, an moment d'emettre dcs preceptes pratiques 

 destines aux voyageurs en montagne et aux aeronautes, a des experiences faites sur des 

 animaux, si convaincantes qu'elles fussent. 



"Je resolus de commencer par experimenter sur moi-meme. J'avais deja, dans mes 

 grands cylindres en tole, subi Finfluence d'assez notables depressions, jusqu'a eprouver 

 certains malaises. Je pensai alors a m'y soumettre de nouveau, pour faire disparaitre 

 les accidents en respirant un air suroxygene. 



'•Je pla^ais alors ji c6te de moi, dans i'appareil, im grand sac de caoutchouc, con- 

 tenant un air d'autant plus riciie en oxygene, que la depression devait etre plus forte," 



The first experiment of this nature was made by M. Bert upon himself 

 on February 20, 1874. He shut himself up in a metal cylinder, with his 

 bag of oxygen, and had pressure reduced in 35 minutes to 450 millimetres, 

 and remained at that pressure, or a little lower, during 68 minutes. After 

 this, air was gradually let in, and in 25 minutes more he returned, so to 

 speak, to the level of the sea. The lowest pressure to which M. Bert was 

 subjected on this occasion was about equal to that which reigns at the summit 

 of Mont Blanc, and before this point was reached he experienced both nausea 

 and dizziness, and his pulse rose from 64 to 100. He refreshed himself with 

 oxygen from time to time with beneficial effects, and found that he could 

 reduce the rate of his pulse, in two minutes, from 90 to 69. This experiment, 

 from first to last, extended over 128 minutes. 



Upon March 9, 1874, a second experiment of this nature was made in 

 M. Bert's apparatus by MM. Croce-Spinelli and Sivel, and upon this occasion 

 pressure was reduced in 37 minutes to 304 mm., which is about equal to that 

 which would be experienced at a height of 24,000 feet above the sea. The 

 experimenters remained, however, only a very short time under this pressure. 

 In 7 minutes they returned below what is the equivalent of the height of 

 Mont Blanc, and in 59 minutes from the commencement of the experiment 

 returned to the level of the sea. Like M. Bert, they refreshed themselves with 

 oxygen, but their pulses nevertheless rose to 132 and 135 ; and, at the lowest 

 pressure, they experienced a sort of drunken sensation, and could neither see 

 nor hear clearly. 



In these two experiments, said M. Bert (p. 758), 



"Toxygene n'avait ete employe que d'une maniere intermlttente, pour diminuer pen- 

 dant qiielques instants la gravite des accidents de la decompression. Je voulus operer un 

 peu difieremment, laisser arriver les malaises jusqu'a un certain degre, pour respirer alors 

 d'une maniere continue Pair suroxygene, tout en continuant a diminuer encore la pression 

 barometrique, et voir ce qui adviendrait." 



Before these further laboratory experiments were made, MM. Croce- 

 Spinelli and Sivel repeated their experiences, this time in balloon, and upon 

 March 22, 1874, rose until they attained a height of about 24,000 feet. As 

 iDefore, they took occasional draughts of oxygen ; but they remained a much 

 greater length of time above the height of Mont Blanc, and were more per- 

 ceptibly affected, especially M, Croce-Spinelli, who endeavoured to eat at the 

 greatest elevation. His pulse rose to 140. 



