nadelewitz Loc: Ithaca NY

Could it have been a viewer for Minox film?

CPR Loc: Nature Coast of Florida

Appears to be a viewer for 35mm film strips. We usually cut the developed film into strips of 5 shots and each strip could be fed in, viewed, and then marked with the grease pencil.

PhotogHobbyist Loc: Bradford, PA

To me it looks like it could be a sort of projection device for glass microscope slides. Putting a slide into the slot and shining a bright light through from the small opening, shown in the second photo, could have projected the image onto a screen. Thus allowing a group of students to see the specimen on the slide, rather than using individual microscopes or each person taking a look through one microscope.

SteveFranz Loc: Durham, NC

I agree that it's a microscope slide viewer. I had one when I was a teenager, about 65 years ago.

Gilkar

That's exactly what it is. The used to be advertised in the back of comic books along with the Charles Atlas ads, etc. I bought one as a kid of about 12 yrs. old. I had fun with it for a while, then lost it. I can remember looking at ants after I smooshed one or two, as well as a plethora of other things. It was a low magnification thing but it was better than a magnifying glass. Of course, my magnifying glass was a cheap one from the 5&10 when such items really were 5 and ten cents. Yours appears to be better constructed than mine was. Back in those days, (the 50's), I'm thinking it was a cheap Japanese knock-off of a better and more powerful German model.

Reuss Griffiths Loc: Ravenna, Ohio

My guess is that it's lens with a opening to insert different transparent grid patterns to be superimposed on whatever is being viewed.

SuperflyTNT Loc: Manassas VA

And your guess is wrong. If you read the thread you would know it’s been identified.

Reuss Griffiths Loc: Ravenna, Ohio

And perhaps I am wrong, but I would be surprised if German optics were advertised in the back of comic books. By design, it definitely appears to be an eyepiece intended to be inserted inside the tube of a microscope where eyepieces of different magnifications are normally inserted. The raised ring around the base of the piece is designed to hold it inside that tube. Additionally, more modern eyepieces can be disassembled and small glass discs with graduations on them inserted to measure items being viewed in the microscope proper. I think this device is a precursor of those.

If it is as you suggest, a magnifier for holding slides to be viewed, I think that any slide inserted into that little slot has a good chance of smearing the subject to be viewed. There also does not appear to be anyway to focus the device on the inserted slide. And lastly, it is an eyepiece, designed to be held up to the eye. It would be awkward holding that up to your eye and looking thru it to a light source. Just sayin'.....

SuperflyTNT Loc: Manassas VA

And a simple google search of “pocket microscope” will return several items just like this. The box clearly shows what appears to be a laboratory slide in the slot. With a fixed distance to the slide the focus could also be fixed, (just like a loupe), and nobody said this was bought from the back of a comic book. They said a similar Japanese knockoff was bought from a comic book.

Reuss Griffiths Loc: Ravenna, Ohio

If you're into simple google searches, try microscope eyepieces (oculars) and ocular reticles, the insertable measuring devices. But the true test is to put a slide in it and see what you can see. Good luck getting any light on it though given the very small aperture at the other end of the eyepiece. Don't expect this will be persuasive but the discussion has been interesting.

SuperflyTNT Loc: Manassas VA

You’re right. It’s not at all persuasive. A microscope eyepiece wouldn’t have that small of an aperture on the bottom and more importantly, it wouldn’t have a slot to insert the slides.