The sun, farther south, in rising and setting, and with limitless changes of polarized and refracted light, passing through strata of atmosphere of varying depths of different density, produces kaleidoscopic changes of burning color.
"My Attainment of the Pole"
Frederick A. Cook
In spite of their efforts, though, first one and then the other leading, no path was found; and at last, in utter despair, after being driven back again and again by the density of the jungle, they were compelled to sit down amongst the bushes edging the forest to wait for day.
"One Maid's Mischief"
George Manville Fenn
density of population and the accompanying excessive competition in the struggle for existence also play a part.
"History of the United States, Volume 6 (of 6)"
E. Benjamin Andrews