Astounding Stories of Super-Science August 1931: VOL. VII, NO. 2 - If The Sun Died

By our system of time we would have called it around 65,000 A. D., but in this cavern world, miles below the long-forgotten surface of the earth, it was 49,889. Since the Death of the Sun. That legendary sun was but a dim racial memory, but the 24-hour day, based on its illusory travel across the sky, was still maintained by uranium clocks, by which the myriads who dwelt in the galleries and maze of the under-world warrens regulated their lives.