CHAPTER V. 

 The Magnitude of the Atmosphere. 



THE total quantity of air of which our atmos- 

 phere is composed is another of the arbitrary 

 magnitudes of our terrestrial system ; and we 

 may apply to this subject considerations similar 

 to those of the last section. We can see no reason 

 why the atmosphere might not have been larger 

 in comparison to the globe which it surrounds ; 

 those of Mars and Jupiter appear to be so. But 

 if the quantity of air were increased, the structure 

 of organized beings would in many ways cease 

 to be adapted to their place. The atmospheric 

 pressure, for instance, would be increased, which, 

 as we have already noticed, would require an 

 alteration in the structure of vegetables. 



Another way in which an increase of the mass 

 of the atmosphere would produce inconvenience 

 would be in the force of winds. If the current of 

 air in a strong gale were doubled or tripled, as 

 might be the case if the atmosphere were aug- 

 mented, the destructive effects would be more 

 than doubled or tripled. With such a change, 

 nothing could stand against a storm. In general, 

 houses and trees resist the violence of the wind ; 

 and except in extreme cases, as for instance in. 



