Hal.—I never saw a dragon-fly drop on the water, or taken by a fish; and salmon sometimes rise even in the salt water, where dragon-flies are never found. There is no difficulty in explaining why salmon in inland rivers should take flies, where natural flies are abundant; but fish, when they have lain long in pools in the river and fed on natural flies, will no longer take these bright flies, and then even a trout-fly is often most successful. I have sometimes thought that the rising of salmon and sea trout at these bright 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, for a month or two after they are hatched, feed like young trouts—and in March and April the spring flies are their principal nourishment. 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.
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 the rainbow is in the east, and in the morning in the west; and as our heavy rains, in this climate, are usually brought by the westerly wind, a rainbow in the west indicates, that the bad weather is on the road, by the wind, to us; whereas the rainbow in the east proves, that the rain in these clouds is passing from us.