"It is a symbol of Irish art. The cracked lookingglass of a servant." -- James Joyce
Another Science Experiment to Try with the Kids
Isaac Newton, early in his investigation of optics, apparently took a bodkin -- a thin dagger, as I understand it -- and slid it between his eyeball and the bones of his eye socket. He then pressed it against the back of his eyeball at various places to see what visual effects were produced.