A mining heir and an elderly inventor drill straight down in an iron mole and come out five hundred miles below, in a land lit by a central sun where reptiles keep men as cattle. Burroughs wrote it in 1913, a year after Tarzan, and gave Pellucidar the one thing Barsoom lacked: no horizon, no night, and therefore no way to measure time. The hero's first act on arriving is to fall in love; his second is to be sold. Fifty-nine plates by painters including Adolph von Menzel and Henry Pether turn on the same moonless, horizonless light that rules Pellucidar, from cloud studies to Westminster Bridge by moonlight.