" On the island at our right was the machine they call the Nilometer, a stone-column whose business it is to mark the rise of the river and prophecy whether it will reach only thirty-two feet and produce a famine, or whether it will properly flood the land at forty and produce plenty, or whether it will rise to forty-three and bring death and destruction to flocks and crops—but how it does all this they could not explain to us so that we could understand. "

― Mark Twain , The Innocents Abroad