"The Gable Window"

by August Derleth
originally published Saturn, July 1957

art by John Coulthart

In 1924, The Unnamed Narrator moves into his cousin Wilbur's remote, strange old house in the wilds of Vermont after Wilbur kicks over.  The house has weird architecture, and its oddest feature is a great round window in the "gable" room.

After living in the house for awhile, UN begins to have strange thoughts and feelings about the room - in other words, it's got Bad Mojo.  And sometimes he hears what sounds like large animals rattling around outside the round window, trying to get in.

Eventually, UN finds a last letter from Wilbur, instructing him to destroy certain papers, donate certain books to Miskatonic U, and smash the round window - smash it I say!  The books turn out to be the usual Cthulhoogie Library Selections.  And even though UN can barely read them and doesn't understand them, he apparently absorbs quite a bit out of them, leading to a long name-dropping paragraph of the usual suspects.

He also finds a bunch of notes left by Wilbur, suggesting that he (Wilbur, that is), believed the glass in the window to be of  "Hyadean" origin, and that he was seeing visions in it -of various Mythos-y places and things, which he described and sometimes drew.  UN figures ol' Wilbur was tipped over.

But, eventually he figures out Wilbur's little ritual used to see visions in the glass, which involves a star-symbol chalked on the floor in front of the window.  And, of course, he has to try it out.

Well, first he sees the desert, then a cave, then some bats, then some "Sand Dwellers" (which also apparently see him), and then a tentacle-faced thingie that starts not only moving towards him in the glass but coming through the glass!

Fighting off fear, UN rubs out part of the chalk star and hurls a shoe at the glass, shattering it and ending the extra-dimensional invasion.  But a severed tentacle is left on the floor - a tentacle "no living savant could identify as belonging to any known creature, living or dead, on the face or in the subterranean depths of the earth!"

(One is left to wonder about the opinions of any dead savants...)

A very minor tale, with, as is not untypical of Derleth, a few atmospheric moments.