Reflection in two parallel plane mirrors: multiple images of an object placed between them.
From El mundo físico: gravedad, gravitación, luz, calor, electricidad, magnetismo, etc. / A. Guillemin. - Barcelona Montaner y Simón, 1882.
(source)
Bertrand Fleuret — via & more — site
[you can download the whole .pdf file]
“I am alone. Walking at random. Wandering, as if at random,...
Peter Upward.
August Strindberg.
From The Lodger, Alfred Hitchcock, 1927.