200 Historical 



the memoir mentioned above of the Physicists of Florence, printed 

 in 1667. 



This noteworthy work is divided into several parts: 



In the First, Boyle questions whether aquatic birds, which can 

 remain for some time under water "because of the peculiar struc- 

 ture of certain vessels which they have around the heart", could 

 sustain better than other animals the lack of air in a pneumatic 

 machine. And, after an experiment made on a duck, he replies in 

 the negative. 



In the Second and the Third, Boyle reports the results of ex- 

 periments made on snakes and frogs, which sustained the vacuum 

 for a long time. 



In the Fourth, he says that he experimented on new-born kit- 

 tens, and that he was astonished to see that these animals held 

 out three times longer than older animals of the same size could 

 have done. 



Part V. Experiment to find out the volume of air contained in 

 the pores of water. 



Parts VI and VII. On the effect of the vacuum upon oysters, 

 crabs, and a gudgeon. 



Part VIII. Experiment on a bird and a frog enclosed in the pneu- 

 matic machine, both having the abdomen opened. 



Part IX. Experiment on the heart of an eel. 



Part X. Comparison of the time it takes to kill animals in water 

 and in the pneumatic machine. 



In Part XI, Boyle reports the sufferings of which Acosta com- 

 plained in his trip over Pariacaca, and he declares that he had 

 heard similar reports from travellers who made the ascent of 

 Mount Ararat, the Peak of Midi, the Peak of Teneriffe, and even 

 the Cevennes. In Chapter I we quoted these different observa- 

 tions. He asks himself in this regard 



Whether the difficulty of breathing which certain persons expe- 

 rienced on the heights of Pariacaca, and perhaps on some other very 

 lofty mountains, comes solely from the lack of elasticity in the air in 

 these high places; whether we should not attribute it, at least in part, 

 to certain penetrating vapors with which the air may be laden in 

 places. (P. 42.) 



Part XII. Effects produced upon an animal by the alternate rare- 

 faction and condensation of the same air. 



Part XIII contains the account of a very remarkable experi- 

 ment, which Magnus was to repeat, more than a century and a 

 half afterwards: 



