The "X=ray" card above is nothing less than a much earlier, non-stereo version of the famous "X-ray" specs, spex, and gogs famous from Boomer-era comic book ads:
Then we have the same thing, only with a "metal base" and called an "X-ray Electroscope." (Ad found by me in the Feb., 1902 issue of The American Boy magazine.) "See your fellow, best girl, or any object through wood or stone," it says, but what about curtains and blinds? Was there another "electroscope" for that?
Could any of these have survived? I ask because, not only were these things from the pre-plastic era, they were likely not constructed to last "a lifetime," unless maybe we're talking, say, the earthly span of a moth. Somewhere, in some forgotten landfill, one of these is sitting next to a quickly discarded Wonder Tube:
Can we assume that the Rogen X-ray (X-ray Wonder), shown directly below in a 1920 ad, worked just as well as the Wonder Tube and X-ray Electroscope? I think we can. I think we can also conclude that, in all probability, "Rogen" was intended to be confused with "Röentgen," as in, X-ray inventor Wilhelm Röentgen. Easy to see through that ploy.
For an explanation of how this highly underwhelming (but quite lucrative!) gimmick worked, so to speak, see Wikipedia's entry on X-Ray Specs: Wikipedia's entry on X-Ray specs. Throughout this piece, I've been using a lower-case r for "Ray," but since we're not talking the genuine phenomenon, I x-spec it doesn't ray-ly matter.
Coming soon: Yet more scopes, including the