yellow tulips viewed through an old water lens
(just found this description of an identical lens):
Industrial water lens. Clear, blown glass circa 1890 -about 12 inches in diameter . - lacemakers or jewelers condenser.
Lenses like this one were used by jewelers, watchmakers, engravers, and by opticians. Water lens and water globes were used as lighting and reading aids.
From a description of the same lens I found on the internet: “ This lens” (the one I found reference to) “was used in the laboratory or workshop of Dr. Charles J. Welsh, Optomologist …. His nephew remembered him using it by filling it with water and letting the sun shine through it when he was doing very fine work on his glasses. In this manner it of course worked as a condenser or magnifier” (additional description in the comments)