We can thank this gizmo for the slide projector and the modern day power-point presentation. It worked by projecting light from a flame or bulb onto a mirror and across glass sides.Turn out the lights and the image could be projected on a wall.  

Versions of the Magic Lantern date back to the 17th century, but its use in education began in the late 1800s in Germany. In 1872, it caused a sensation when it was demonstrated in the U.S.  

The first machines used lamp oil, then limelight and finally electric bulbs in the 1890s.

The introduction of film and overhead projectors to the classroom in the 1930s, was a threat to the Magic Lantern. But it hung on well into the 1950s, and many academic institutions still archive their glass slides.

The world the has changed a lot since the 19th century, and an old image can speak 1,000 words about the days gone by.