Crawford Tillinghast's House

An ordinary house whose upper room now contains a resonance machine built to stimulate the pineal gland and reveal what ordinary senses are built to filter out. It works exactly as advertised, which is the whole problem.

Whereabouts: An unspecified New England residence Tillinghast has had fitted, at some expense, with a private laboratory in an upper room.

Access: By personal invitation — the narrator is one of the only people Tillinghast still keeps in contact with, which turns out to be exactly why he's invited.