I fix in a prominent situation a large and vertically revolving fan, of a light and vibrating substance.

The movement of the air causes this to rotate by the mere force of the impact.

The rotation and the vibration of the fan convert an irregular impulse into a steady and equable undulation; and such is the elasticity of the fluid called, in popular language, 'the air,' that for miles around the rotation of this fan regulates the circulation, modifies extremes, annihilates sterility, and makes it quite impossible for moss and green scum and all this sour growth to live.

Even you can see, Mary, how beautiful it is." "Yes, that I can," she answered, simply, as they turned the corner upon a large windmill, with arms revolving merrily; "but, Willie dear, would not Farmer Topping's mill, perpetually going as it is, answer the same purpose?
And yet the moss seems to be as thick as ever here, and the ground as naked." "Tush!" cried Willie.

"Stuff and nonsense! When will you girls understand?
Good-by! I will throw away no more time on you." Without stopping to finish his sentence he was off and out of sight both of the mill and Mary, before the poor girl, who had not the least intention of offending him, could even beg his pardon, or say how much she wanted him; for she had not dared as yet to tell him what was the purpose of her walk, his nature being such that no one, not even his own mother, could tell what conclusion he might come to upon any practical question.