The time at night!
Did Trouvé also invent the night light clock? We found this engraving in “La Nature”, dated February 1884.
Projection clocks were patented at least twice: once in 1909 in the UK, and another time in 1940. Both patents have expired.
Today, without looking at either the wall or the ceiling, everyone can check what time it is, lit up on the tiny screen of their cell phone, tablet or computer.