Yet another blog post about invisibility in fiction! Just as a reminder, this is to celebrate the completion of my book draft on the history of invisibility physics, coming next year (I hope).

Let me recap and build upon a list I started a few posts ago: so far, we’ve had invisible people, invisible monsters, invisible buildings, invisible cars, invisible dogs, invisible spacecraft, invisible robots, and invisible superheroes. But we haven’t yet seen invisible aliens, so let’s rectify that!

Today’s story is from another addict of invisibility, Captain S.P. Meek, who also wrote “The Cave of Horror,” which appeared in the January 1930 issue of Astounding Stories of Super-Science. Fast forward to September of 1930, and we find that Meek has another story, “The Attack From Space!”

As noted in the image, this story is a sequel to Meek’s “Beyond the Heaviside Layer,” which appeared in the July 1930 issue of the same magazine. So, before we get to this story, we have to say a few words about what “the Heaviside layer” is…

The Heaviside layer is a layer of ionized gas surrounding the Earth at roughly 100 km above the surface. Its existence was predicted independently by Arthur Edwin Kennelly and Oliver Heaviside in 1902, and hence it is also known as the Kennelly-Heaviside layer. This layer is noteworthy because, consisting of a bunch of free electric charges, it is very good at reflecting radio waves, and thus allows radio signals to be received at locations below the horizon of the radio source. These waves don’t go straight from source to receiver, but instead bounce off the Heaviside layer first.

This idea of a “barrier” to radio waves seems to have inspired Captain Meek to imagine the Heaviside layer instead as a solid, viscous fluid that surrounds the Earth. In “Beyond the Heaviside Layer,” a rocket engineer named Jim Carpenter takes a journalist named Bond up in a rocket and they blast their way through the layer, finding all sorts of strange and alien creatures beyond.

The sequel, “The Attack From Space,” is basically about the aftermath of their adventure. The hole that Carpenter blasted through the layer does not close right away, and is essentially a tunnel to space for years. During that time, other intelligent beings take advantage of Earth’s vulnerability and send scouting missions to collect human beings to serve as slaves in their radium mines on Mercury. Of course, the alien spacecraft are invisible, so witnesses report seeing abductees floating up into the air with nothing else in sight!

Carpenter and Bond leap into action to track down the invaders and, as seen in the first image of this post, are captured themselves. They have to wait for the right moment to save themselves, the abductees, and possibly all of humanity!

So how do the alien beetles achieve their invisibility? As Carpenter explains it,

“Have you solved the secret of their invisibility?”

“Partly. It is as I expected. The walls of the ship are double, the inner one of metal and the outer one of vitrolene or some similar perfectly transparent substance. The space between the walls is filled with some substance which will bend both visible and ultra-violet rays along a path around the ship and then lets them go in their original direction.”

“Vitrolene,” as far as I can tell, is some sort of clear varnish. The description given here is qualitatively close to the description of modern theoretical invisibility cloaks, which guide light waves around a central region and send them on their way. Again, here are the images from the two original 2006 papers, showing how light rays could be bent around a cloaked region:

Part of the challenge for real invisibility cloaks, however, is that it is not possible to make a passive cloak that simply guides light waves that will operate effectively in both the visible and ultraviolet regime. In fact, passive cloaks can only operate effectively for a very small range of wavelengths, like a very specific shade of red. There are ways to get beyond this limitation, but that’s a story for another blog post!

By the end of “The Attack From Space,” most of the invaders have been killed, except for one who has been allowed to return home as a warning to the other Mercurian beetles. But Jim isn’t quite satisfied:

“I hope I’ve seen the last of those bugs,” I said as the flyer faded from view.

I don’t know,” said Jim thoughtfully. “If I have interpreted correctly the drawings that creature made, there is a race of manlike bipeds on Mercury who are slaves to those beetles and who live and die in the horrible atmosphere of a radium mine. Some of these days I may lead an expedition to our sister planet and look into that matter.”

Clearly, Captain Meek was setting up a potential sequel! Did Jim ever rescue the slaves of Mercury? I haven’t found a sequel story yet, but stay tuned…

PS I have to share a snapshot of the table of contents description of the story. The grammar of “because invisible” just makes me chuckle.

PPS you may be familiar with the term “Heaviside Layer” from another source, where it is inexplicably used as Heaven for a collection of humanoid felines. But the less we say about this, the better.