A mighty host of gray clouds, piled thickly one upon another, and torn and tunneled by feverish wind-gusts, were hastening swiftly and silently across the sky from the west.

Beyond, where they were thickest and angriest, a yellowish, lurid tint was reflected against them.

The valley darkened like a frowning face, and the summits of the western hills were blotted out of sight.

A lightning-flash shivered brightly through the air, and then came the first growling, leaping, accumulating peal of thunder.

A sudden, rustling breath swept through the garden, and, following it, in big, quick drops, and soon in an unintermittent myriad-footed tramp, the rustling, perpendicular down-pelting of the rain.
In less than a minute, a gray, wet veil had been drawn across the farther side of the valley, hiding it from the professor's sight.