At first it was like strings of water, afterwards ropes, and in the end it seemed as if whole rivers were flowing from invisible clouds.
"In Desert and Wilderness"
Henryk Sienkiewicz
Stas, seeing her grief, was angry at himself because he had not concealed the danger from her and began to comfort her: "I would go after them with the rifle," he said, "but they must now be very far away, and soon the night will fall and the tracks will be invisible.
"In Desert and Wilderness"
Henryk Sienkiewicz
The dogs, of themselves, followed the invisible line of tracks.
"My Attainment of the Pole"
Frederick A. Cook