Oh, and one more thing. The Spider novel for December 1939 was SATAN'S MURDER MACHINES. The main villain is known as the Iron Man (you know, maybe Stan did devour the Spider pulps as a young man, as he acknowledged). This fiend leads a squad of a dozen killers who climb inside suits of motorized armor to cause mass destruction. It's not clear exactly how big these "robots" are. At one point, one of them has its head almost reach a street light, and another one is able to hide inside a wine cellar in ambush. Maybe they come in different models, like cars. The robots show up, chuckling at police bullets and hand grenades, pushing over buildings so they can loot and pillage. I love the visual detail about these monsters, "the mouth had teeth like a steam shovel."