Elsewhen
It was first published as "Elsewhere" in the September 1941 issue of "Astounding Science Fiction" , under the pen name Caleb Saunders , and was reprinted in the 1953 book "Assignment in Eternity" , with some minor changes , and an additional character and that character's journey . 
<triplet> Assignment in Eternity <subj> 1953 <obj> publication date