Theories and Experiments 197 



on simultaneously with observations made by travellers. But 

 strangely enough, for a long time physicists tried exclusively to 

 study the effect of a vacuum, that is, the total lack of air. They 

 did not inquire what would happen from a sojourn in air which 

 was merely rarefied; for them, it seems, only two possibilities 

 existed: to have air or to have no air. And yet, by a strange 

 contradiction, many of them, trying to find out why animals which 

 are kept in closed vessels die, were convinced that it was because 

 of "the decrease in the elasticity of the air". Very strange! They 

 did not investigate experimentally to see what would happen to 

 animals which were subjected to such a decrease from the very 

 outset; after the famous experiments of Pascal on the Puy-de- 

 Dome (September 22, 1648), they were not surprised to see ani- 

 mals continuing to live, which, on the mountains, were subjected 

 to a decrease in the elasticity of the air enormously greater than 

 that which accompanies asphyxia in closed vessels. 



At any rate, the members of the famous Academy del Cimento 3 

 tell us that: 



As soon as Torricelli first advised the experiment with mercury, 

 he began to think also how he would imprison different animals in 

 a vacuum, so as to observe in them movement, flight, respiration, and 

 all the other phenomena which could be observed. But being without 

 the instruments necessary for this sort of experiment, he did the best 

 he could. For the small and delicate animals were overwhelmed by 

 the. mercury, through which they had to climb upward, when next 

 the vessel was overturned and they were plunged into the other 

 mercury. And they were then quite or almost dead, so" that one 

 could not tell whether they were injured more by the mercury which 

 suffocated them or by the lack of air. (P. 46.) 



As for them, they tell in their memoirs for the year 1667 the 

 numerous experiments they made on animals, using barometric 

 tubes, the large chamber of which was closed by a bladder. 



These animals were leeches, snails, insects of different sorts, 

 reptiles, and birds. The experiments give with remarkable exact- 

 ness the different symptoms displayed by these animals which 

 were subjected instantaneously to an almost perfect vacuum. The 

 physicists of Florence noticed besides that, in fish placed in the 

 vacuum, the "air bladder" deflated and the fish then remained at 

 the bottom of the water; in consequence, they performed curious 

 experiments, thanks to which they discovered the "little vent-hole" 

 through which the air escapes when it is expanded by the effect 

 of the diminution of pressure. 



We do not find in this account any very definite theoretical 



