Letters in the Sky
In 1933, a German ship cruising in the Baltic sea projected letters onto the clouds in the night sky using a giant searchlight. Here is a dramatic
photo.
The same year, airplanes in the USA were equipped with "player piano" rolls which controlled lights to form
huge letters across the wings.
Speaking of letters in the sky, I love this quotation from
Jonathan Strange and Mr. Norrell by Susanna Clarke (one of the most enjoyable books I've ever read, by the way):
The only live, bright things were the stars. Their constellations looked to Drawlight like gigantic, glittering letters—letters in an unknown alphabet. For all he knew the magician had formed the stars into these letters and used them to write a spell against him.
