Question: Which American writer and researcher born in 1874 proposed the existence of a dimension into which lost things go and called it The Super-Sargasso Sea? 
Sentence (from "Super-Sargasso Sea"): Fort did not actually believe that it existed but, in the vein of the ancient Greek skeptics, he wished only to present a theory that was just as plausible as those in the mainstream.
Relevant evidence: No