144 THE BORDERLAND OF SCIENCE. 



the balloon had come down again to the same level. 

 At 37,000 feet Coxwell could no longer use his hands, 

 and was obliged to pull the string of the valve with 

 his teeth. A few minutes later he would have swooned 

 away, and probably lost his life. The temperature of 

 the air was at this time twelve degrees below zero.' 

 This certainly does not suggest that life on the earth 

 would be pleasant, if the air were reduced in quantity 

 to that above the level reached by Coxwell and Grlaisher 

 on this occasion. But the barometer still stood nearly 

 seven inches high when they began to descend, at 

 which time Grlaisher was nearly two miles above his 

 fainting level, while Coxwell was all but powerless. 

 And then it is to be remembered, as Flammarion well 

 remarks, that in balloon ascents ' the explorer remains 

 motionless, expending little or none of his strength, 

 and he can therefore reach a greater elevation before 

 feeling the disturbance which brings to a halt at a far 

 lower level the traveller who ascends by the sole strength 

 of his muscles the steep sides of a mountain.' What 

 would be the state of a traveller having to exert him- 

 self in an atmosphere reduced to five-sevenths of the 

 density of the air in which Coxwell was just able to save 

 his own life and Grlaisher's, literally ' by the skin of 

 his teeth'? 



To show the effect of active exertion in increasing 

 the unpleasant results of great atmospheric tenuity, we 

 may quote the experience of De Saussure, in his ascent 

 of Mont Blanc, noting however that recent Alpine 

 travellers seem to have been more favoured, while the 



