The hammer rang once. A spark jumped off the anvil and did not go out. It waited. They followed.

It rolled into the little museum on the Green and settled on the loan desk, beside the date stamp.

On the shelf behind Ledger, a mended clock ticked. A tiny hammer was painted on its face.

"Last slip in your folder," said Ledger, and lifted a small copper bowl out of a box lined with cloth. It was round and thin and very light.

This time Beto wrote the slip, and he did not rush.

A round copper bowl, thin, light. The inside is darker than the outside. There is a tiny hole in the very bottom, smaller than a pinhead. There is a line scratched inside, near the rim.

On the second line he wrote: I think it is broken. It has a hole.

The note in the box said: A sinking-bowl water clock. In India it was called a ghaṭī.

"A clock with a hole in it?" said Beto.

A small green frog hopped out of the box of cloths. This was Cup, who loved filling things.

"Mark the water line," said Cup happily. "Then watch."

Cup filled a wide tub with water and set the copper bowl floating on top, like a little boat.

At first nothing happened. Then Lan saw a thin thread of water coming up through the tiny hole, into the bowl. Slowly. Always the same speed.

The water inside the bowl crept up. The bowl sat lower and lower.

"Fill it till it touches," said Cup.

When the water inside touched the scratched line, the bowl tipped, wobbled and sank to the bottom of the tub with a soft clunk.

"The water keeps count for you," said Cup.

"How long did it take?" asked Beto.

"I'll time it," said Lan. Cup scooped the bowl out and floated it again.

"One elephant, two elephant, three elephant," said Lan.

At a hundred and twelve elephants, she sneezed. At two hundred she wasn't sure if she had said two hundred already. At three hundred she stopped. "I've lost count," she said.

A round alarm clock with a smiling face was standing on the shelf. This was Tick.

"Count with something that doesn't hurry," said Tick. "Your elephants speed up when you're excited. They slow down when you're bored. Steady, steady."

Tick watched the bowl from the moment it touched the water.

It sank. Tick looked at the clock hands. "Twenty-four minutes," said Tick.

They floated it again. Twenty-four minutes.

"Every time," said Beto.

"That is why it is a clock," said Tick. "Anything that happens at a steady rate can measure time. A swinging weight. A burning candle. A bowl that fills."

Ledger read the rest of the note. "Long ago, timekeepers floated a bowl like this all day and called out each time it sank. Sixty sinkings made one whole day and night."

Beto did the sum. Sixty times twenty-four. "One thousand four hundred and forty minutes."

"And twenty-four hours of sixty minutes?" asked Tick.

"One thousand four hundred and forty," said Lan. "The same."

Lan floated the bowl herself. She did not count elephants. She just watched.

When it sank, she lifted it out, emptied it, and floated it again at once. When it sank the second time, she called out.

"Now!"

Tick looked at the hands. "Forty-eight minutes. Right on."

Lan dried the bowl gently with a soft cloth and finished the last slip. Object returned, condition good, dried with a soft cloth. Learned: anything steady can measure time. The hole was not a mistake.

Ledger stamped it. The children's folder was full.

Back on the Green

The spark dimmed to a warm dot and settled back on the anvil. The Green was just the Green again.

At bath time, Lan poked a tiny hole in an old yoghurt pot and floated it.

She looked at the kitchen clock and waited.