Do not mistake these letters to be written simply on a chalkboard. The letters have been actually made by water falling down in a calculated manner. For an observer it produces the illusion of letters being printed in thin air with a scrolling effect.
In addition to letters, patterns and numbers [that depict the current time] can also be visualized with the help of this bemusing mechanism titled Space Printer. Devised by the Koei Industry the water art contraption can be seen at the Osaka Station City complex in Japan.
Check out the video below for an entertaining water show.