Charles Willard Diffin  (1884-1966) US engineer, airplane salesman and writer who graduated with a degree in analytical chemistry from the University of Buffalo, New York. He was most active with the magazines published by William Clayton and Street & Smith. He was one of the better writers whom Harry Bates encouraged to write for the new Astounding Stories, though he rapidly descended into formulaic fiction.

His first, "Spawn of the Stars" (February 1930 Astounding), has Earth invaded by amoeba-like Aliens and was sufficiently competent for Groff Conklin to reprint it in The Best of Science Fiction (anth 1946) but was the first of several routine world-saving adventures in the style of Edmond Hamilton.

In this ebook:

The Finding of Haldgren
Brood of the Dark Moon
Two Thousand Miles Below
The Hammer of Thor