Yet another post about invisibility in fiction! Will I ever run out of these? I feel like I need to write another book just about invisibility fiction.
So in my last post, I wrote about “Invisible Death”, which appeared in the January 1930 issue of Astounding Stories of Super-Science. On a whim, I happened to browse the rest of the stories, and found another story about invisibility in that same issue. Clearly invisibility was a hot topic in that era.
The new story I found is titled “The Cave of Horror,” by Captain S.P. Meek.
It is a mixture of horror, action, and science fiction, and features run-ins with an invisible monster that has wandered up from the bowels of the earth and is now haunting Mammoth Cave, in Kentucky!
The story begins in the laboratory of Dr. Bird, a researcher at the Bureau of Standards. He is paid a visit by Operative Carnes of the United States Secret Service, who has come with a mystery needing to be solved that is too intriguing for Bird to pass up. Recently, a group of tourists — and their guide — went missing in the twisting passages of Mammoth Cave. When a search party was sent in, two members failed to return. This led to the National Guard being deployed, and they started disappearing, too, leading to the U.S. Army being called in. And those soldiers, as the accompanying illustration to the story above shows, were attacked by something that could not be seen! By the time of Carnes’ visit, the Cave has been cordoned off, and nobody allowed inside.
Bird finds himself unable to resist getting to the bottom of the mystery, and he accompanies Carnes to the site. Once there, Bird makes preparations to see if he can photograph the unseen and find out what they’re dealing with. But those risks might turn fatal if they’re not careful…
“The Cave of Horror” turned out to be a pleasant surprise, considering how many mediocre invisibility stories I’ve read recently! The invisible threat turns out to be an almost Lovecraftian horror from the darkest depths of the earth, one that has found its way to the surface and has concluded that humans are a tasty treat. The descriptions of the creature, once Bird manages to get a photograph of it, are delightfully weird.
What made me particularly happy is how the author Meek clearly had some knowledge of optics! The physical explanation of the creature’s invisibility is the familiar “the creature is of an ultraviolet color” variety, that was first used by Ambrose Bierce in his horror story “The Damned Thing.” When Bird tries to take a photograph of the creature, he gives a detailed explanation of his photographic apparatus and the physics behind it. A description of the device:
“The system of reflectors catches all of the light thus produced except the relatively small portion which goes initially in the right direction, and directs it on this quartz prism where, due to the refractive powers of the prism, the light is broken up into its component parts. The infra-red rays and that portion of the spectrum which lies in the visible range, that is, from red to violet inclusive, are absorbed by a black body, leaving only the ultra-violet portion free to send a beam through this quartz lens.”
Some musings about why a creature might be invisible is given soon after:
“The longer rays of visible a light given will not penetrate as deeply into a given substance as the shorter ultra-violet rays. This visitor is evidently from some unexplored and, indeed, unknown cavern in the depths of the earth where visible light has never penetrated. Apparently in this cavern the color of the inhabitants is ultra-violet, and hence invisible to us.”
A bit more description shows some pretty solid optics knowledge, in explaining that the creature must be transparent to visible light and opaque to the ultraviolet:
“If we fill a glass container with a fluorescein solution and look at it by reflected light it appears green. If we look at it by transmitted light, that is, light which has traversed the solution, it appears red. In other words, this is a substance which reflects green light, allows a free passage to red light, and absorbs all other light. This creature we are after, if my theory is correct, is composed of a substance which allows free passage to all of the visible light rays and at the same time reflects ultra-violet light. Do I make this clear?”
Obviously, these descriptions are not scientifically perfect — after all, as far as we know, invisibility is impossible — but they demonstrate a pretty solid working knowledge of optical physics! For this reason, the story made me quite happy.
Overall, “The Cave of Horror” is a surprisingly fun story. For that reason, I include the pdf on my blog so you can read it for yourself if you so desire.
Captain S.P. Meek would go on to write many more tales for Astounding Stories. Many of these would be the further adventures of Dr. Bird and Carnes, such as “The Black Lamp,” which appears in the February 1931 issue. Meek would also go on to write another story about invisibility for the magazine!
… but that is a story for another day.