INDICATIONS OF RAINY WEATHER. 191 



Phys. — I have no doubt of it, for the red 

 has a tint of purple. 



Hal. — Do you know why this tint por- 

 tends fine weather ? 



Phys. — The air, when dry, 1 believe, re- 

 fracts more red, or heat-making, rays; and 

 as dry air is not perfectly transparent, they 

 are again reflected in the horizon. I have 

 generally observed a coppery or yellow sunset 

 to foretell rain ; but, as an indication of wet 

 weather approaching, nothing is more cer- 

 tain than a halo round the moon, which is 

 produced by the precipitated water ; and the 

 larger the circle, the nearer the clouds, and 

 consequently the more ready to fall. 



Hal. — I have often observed, that the old 

 proverb is correct — 



A rainbow in the morning is the shepherd's 



warning : 

 A rainbow at night is the shepherd's delight. 



Can you explain this omen ? 



Phys. — A rainbow can only occur when 

 the clouds containing, or depositing, the rain 

 are opposite to the sun, — and in the evening 



