HEIGHT OF THE ATMOSPHERE. 109 



have a furious hurricane rushing perpetually round 

 the globe at the rate of one thousand miles an hour, 

 ten times the speed of the most violent tornado that 

 has ever carried devastation over the surface of the 

 earth. 



The air, heated and dried as it sweeps over the 

 arid surface of the soil, drinks up by day myriads 

 of tons of moisture from the sea, so much, indeed, 

 that, were none restored to it, the surface of the 

 ocean would be depressed eight or ten feet annually. 



We do not certainly know the height of the at- 

 mosphere. It is said that its upper surface cannot 

 be nearer to us than fifty, and can scarcely be fur- 

 ther off than five hundred, miles. " It surrounds us 

 on all sides, yet we cannot see it ; it presses on us 

 with a weight of fifteen pounds on every square 

 inch of the surface of our bodies in other words, 

 we are at all times sustaining a load of between 

 seventy and one hundred tons of it on our persons 

 yet we do not feel it ! Softer than the finest down, 

 more impalpable than the lightest gossamer, it leaves 

 the cobweb undisturbed, and, at times, scarcely stirs 

 the most delicate flower that feeds on the dew it 

 supplies ', yet it bears the fleets of nations on its 

 wings round the world, and crushes the most re- 

 fractory substances with its weight It bends the 



rays of the sun from their path to give us the aurora 

 of the morning and the twilight of evening. It dis- 

 perses and refracts their various tints to beautify 

 the approach and the retreat of the orb of day. 



