Correct, glass lanterns typically used in movie houses between shows, sort of a newsreel or coming attraction from the silent era. Not common given the delicacy of the material. I have a few of Jess Willard, the heavyweight champ, but those baseball ones are spectacular. Not any good ways to shoot them casually. What you really need is a light table like for slides. I tried to shine a light behind this Willard v. Jack Johnson one while I scanned it:
Didn't work too well. This one scanned OK with a piece of white comic book board behind it just because the image has sharp areas of contrast.
