The reverberations, too, of the mountains, and the roaring of the forests, are indicative of certain phænomena; and the same is the case when the leaves are seen to quiver,705 without a breath of wind, the downy filaments of the poplar or thorn to float in the air, and feathers to skim along the surface of the water.706 In champaign countries, the storm gives notice of its approach by that peculiar muttering707 which precedes it; while the murmuring that is heard in the heavens affords us no doubtful presage of what is to come.