SIXTH DAY.] INDICATIONS OF RAIN. 163 



flies, as soon as they come from the sea into rivers, 

 might depend upon a sort of imperfect memory of 

 their early food and habits ; for flies form a great 

 part of the food of the salmon fry, which, before 

 migrating to the sea, feed like young trouts ; flies are 

 their principal nourishment ; and in going back to 

 fresh water, they may perhaps have their habits of 

 feeding recalled to them, and naturally search for 

 their food at the surface. 



POIET- This appears to me very probable. But 

 it is late, and we must return and compare the crimped 

 trout and salmon ; and I hope we shall have another 

 good day to-morrow, for the clouds are red in the west. 



PHYS. I have no doubt of it, for the red has a 

 tint of purple. 



HAL. Do you know why this tint portends fine 

 weather ? 



PHYS. The air, when dry, I believe, refracts 

 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 foretel rain ; but, as an indication of 

 wet weather approaching, nothing is more certain 

 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. M 2 



