Palmer enjoyed hoaxes, such as printing a photograph of a writer when in fact the name in question was a pseudonym. In the February 1944 issue of "Fantastic Adventures", he printed a letter in which the writer claimed to be a time-traveling scientist born in 1970, whose time machine was inspired by a story in the magazine. Palmer pretended to take the letter seriously, and printed an appeal to readers to find the scientist. Palmer's most successful hoax was the "Shaver Mystery", a series of stories in which the author, Richard Shaver, explained all the wrecks and accidents on Earth as the result of interference by ancient machinery hidden underground. The series was enormously popular; all the Shaver Mystery stories were published in "Fantastic Adventures" companion magazine, "Amazing Stories" (which led Ashley to describe "Fantastic Adventures" as a "haven" from the Shaver stories) but Shaver did also publish some competent fantasies in "Fantastic Adventures". The increased circulation enabled both "Amazing" and "Fantastic Adventures" to return to monthly publication in the late 1940s.