Water Clock

On any given day, as 1 p.m. approaches, crowds gather in the Sunburst Atrium at The Children’s Museum. They watch in anticipation as blue liquid fills the final glass globe marking the hours on a 30-foot-tall water clock. When all of the clock’s globes—29 small disk-like ones marking two-minute intervals and 12 larger ones marking the hours—are full, they empty with a WHOOSH, leaving the globes ready to refill gradually over the next 12 hours. (The clock also empties at 1:00 a.m. each day, but the only people present to witness that are the museum’s security guards.)

88.194.1, Water Clock, Bernard Gitton, France, 1980s

Always a crowd-pleaser, the clock was designed by a French physicist-turned-artist by the name of Bernard Gitton. He created the museum’s clock—which one of only seven such Gitton creations in the world—in his studio in France, watching as each glass globe, disk, and tube was hand-blown. To work properly, each piece had to be made with precision. When all the parts were done, Gitton assembled and tested the clock, then took it apart and shipped the pieces to Indianapolis where he and two assistants reassembled it and taught staff members how to maintain it.

The clock uses an electric pump, which is installed under the floor, to move a 70-gallon mixture of water, methyl alcohol, and blue food coloring. The pump forces the solution to a reservoir at the top of the clock where it flows into a shallow cup that’s attached to a green neon pendulum. As the cup fills, the weight of the solution causes the cup to dip and empty the liquid into the clock’s pipes every two seconds. The liquid gradually fills the 29 small two-minute disks and every hour the entire column of disks empties—that creates a vacuum, which then causes the solution to fill one of the hour globes.

Together the number of filled disks and globes represent the time. For example, 10 filled disks and four filled globes means it is 4:20 (in either the morning or the afternoon). However, if you do the math, you will realize that 29 disks, each representing two minutes, only equals 58 minutes. What happened to the other two-minutes required to make a 60-minute hour? When all of the clock’s disks and globes empty, it takes two minutes for the pipes to drain. When it’s done, it’s officially 1:00.

Then the process starts all over once the invisible pump sends the blue solution back up to the top of the clock.