CHAP. XIX. PROFESSOR PAUL BERT. 377 



At the end of this highly interesting passage^ by some process 

 of reasoning that is not manifested. Father Acosta shrewdly guesses 

 that the air is ^delicate' at great heights/ and '^is not proportion- 

 able with the breathing of man, which requires a more grosse aire/'' 



Subsequently, when diminution in atmospheric pressure was 

 demonstrated by means of the barometer, men spoke of the effects 

 of ' rarefaction of the air/ though without having a distinct idea 

 how it operated ; and after the discovery of oxygen they began to 

 lay all the troubles to want of oxygen, which it seems to have been 

 thought settled in the atmosphere like sediment in muddy water. 



Latterly, Professor Paul Bert endeavoured to shew that no 

 troubles would occur through diminution in j)ressure (or rarefac- 

 tion of the air) if one imbibed sufficient oxygen ; and he carried on 

 a long series of laboratory experiments with the ultimate aim 

 of offering practical suggestions for the guidance of mountain- 

 travellers and aeronauts. His two final experiments, with the 

 conclusions at which he arrived from them, are related in his own 

 words at the end of this volume. 



It will be seen by reference to Appendix J (where these 

 experiments are given at full length), that Prof. Bert observed the 

 rate of the pulse was accelerated when pressure was reduced, that 

 it fell again when pressure was restored, and that he noticed it 

 was temporarily reduced upon imbibing oxygen. He considered 

 that in the inhalation of oxygen he had discovered a panacea for 

 all ills arising from diminution in pressure, and at the conclusion 

 of his book {La Pression Barometrique) gave various ' practical 

 hints ^ for the guidance of mountain-travellers and aeronauts. 



At p. 1103 he suggests that the former class might carry metal 

 cylinders, weighing 28|- lbs., holding 330 litres of oxygen com- 

 pressed to one-thirtieth of its ordinary bulk, an amount which he 

 calculates would suffice for one man for more than an hour (at 

 what elevation or pressure is not stated) ; and at p. 1061 he 



1 The Barometer had not been invented when Acosta's Natural & Moral History 

 was first printed (1590). 



3 C 



