Two Medical Museums on line had these in their catalogs. The information given was that this nipple shield was made and used around 1910. It was marketed as a Anti-Colic nursing shield nipple. Unusual collectible item.
Amazing the rubber nipple is still pliable although crazed with age. The glass shield is not chipped or cracked. It has a rounded comfort edge.
The glass area is 2" in diameter, the nipple alone is 1 1/2". The total height is about 2 1/2"