So that is what these are... minnow traps. Same principal as a lobster trap, set it on the brook/river floor to catch minnows when you can't afford bait. A company in Michigan has recently bought the mold for these glass traps from Orvis and have recreated them as The Stream and Lake Glass Minnow Trap. Apparently they work better than the wire traps. Sounds reasonable.
Setting Your Minnow Trap (paraphrased from Boys Life)
To use your trap, add some bread or cracker bits. Sink the trap in your favorite pond or lake for a few hours, preferably overnight. Tie it securely to a dock or tree. The minnows will go in the trap but aren’t smart enough to get out. Next morning, simply open and pour the minnows into your bait bucket. You’re all set for a day of fishing!
A few years ago Orvis made a 150th anniversary edition that sold out (at $300).
"Handblown and first launched in 1885, the Orvis Glass Minnow Trap sold briskly for more than 80 years. During World War II, the disruption of the saltwater fishing fleet by German U-boats saw a rise in the trap's orders as traps were used by freshwater fisherman who fished for a living or for sustenance. During the War, the trap played a crucial role in the Orvis Company's survival."
Slight disclosure; I grew up near Manchester VT, home to Orvis, so have a soft spot for anything good they do. Have no business connection with them whatsoever.