h.p Lovecraft 
From Beyond [EPUB ebook] 

'From Beyond’ is a short story by science fiction and horror fiction writer H. P. Lovecraft. The story is told from the first person perspective of an unnamed narrator and details his experiences with a scientist named Crawford Tillinghast. Tillinghast creates an electronic device that emits a resonance wave, which stimulates an affected person’s pineal gland, thereby allowing them to perceive planes of existence outside the scope of accepted reality. Sharing the experience with Tillinghast, the narrator becomes cognizant of a translucent, alien environment that overlaps our own recognized reality. From this perspective, he witnesses hordes of strange and horrific creatures that defy description.