[Image: The Ladybower bellmouth at full drain, photographed by Flickr user Serigrapher].

Nearly half a year ago, a reader emailed with a link to a paper by Andrew Crompton, called "Three Doors to Other Worlds" (download the PDF). While the entirety of the paper is worth reading, I want to highlight a specific moment, wherein Crompton introduces us to the colossal western bellmouth drain of the Ladybower reservoir in Derbyshire, England.

His description of this "inverted infrastructural monument," as InfraNet Lab described it in their own post about Crompton's paper—adding that spillways like this "maintain two states: (1) in use they disappear and are minimally obscured by flowing water, (2) not in use they are sculptural oddities hovering ambiguously above the water line"—is spine-tingling.

[Image: The Ladybower bellmouth, photographed by John Fielding, via Geograph].

"What is down that hole is a deep mystery," Crompton begins, and the ensuing passage deserves quoting in full:

Not even Google Earth can help you since its depths are in shadow when photographed from above. To see for yourself means going down the steps as far as you dare and then leaning out to take a look. Before attempting a descent, you might think it prudent to walk around the hole looking for the easiest way down. The search will reveal that the workmanship is superb and that there is no weakness to exploit, nowhere to tie a rope and not so much as a pebble to throw down the hole unless you brought it with you in the boat. The steps of this circular waterfall are all eighteen inches high. This is an awkward height to descend, and most people, one imagines, would soon turn their back on the hole and face the stone like a climber. How far would you be willing to go before the steps became too small to continue? With proper boots, it is possible to stand on a sharp edge as narrow as a quarter of an inch wide; in such a position, you will risk your life twisting your cheek away from the stone to look downward because that movement will shift your center of gravity from a position above your feet, causing you to pivot away from the wall with only friction at your fingertips to hold you in place. Sooner or later, either your nerves or your grip will fail while diminishing steps accumulate below preventing a vertical view. In short, as if you were performing a ritual, this structure will first make you walk in circles, then make you turn your back on the thing you fear, then give you a severe fright, and then deny you the answer to a question any bird could solve in a moment. When you do fall, you will hit the sides before hitting the bottom. Death with time to think about it arriving awaits anyone who peers too far into that hole.

"What we have here," he adds, "is a geometrical oddity: an edge over which it is impossible to look. Because you can see the endless walls of the abyss both below you and facing you, nothing is hidden except what is down the hole. Standing on the rim, you are very close to a mystery: a space receiving the light of the sun into which we cannot see."

[Image: The Ladybower bellmouth, photographed by Peter Hanna, from his trip through the Peak District].

Crompton goes on to cite H.P. Lovecraft, the travels of Christopher Columbus, and more; again, it's worth the read (PDF). But that infinitely alluring blackness—and the tiny steps that lead down into it, and the abyssal impulse to see how far we're willing to go—is a hard thing to get out of my mind.

(Huge thanks to Kristof Hanzlik for the tip!)