The Emperor was standing on the wall of the Forbidden City overlooking the square outside the Lion Gate. Three dervishes were dancing in the square. They wore tall white hats and long white robes. They turned slowly and the triangle they formed slowly turned as well.
The Emperor sent agents to learn about the dervishes but nothing definite was known. They had recently arrived at the capital, but no one could say whether they came from nearby or from afar or how they traveled. Some said they walked across fields without bending the grain and others said they rode on donkeys. Each dervish stirred up a small dustcloud as he danced in the square. The Emperor sent a messenger to invite the dervishes to visit him in his palace.
The dervishes bowed wordlessly and seemed not to understand anything the messenger said. However they followed him in through the Lion Gate and to the throne where the Emperor was waiting.
The dervishes danced before the throne in the sight of the Son of Heaven. When their dance was finished, they opened their mouths—from the first one's mouth came red light, from the second came green, and from the third came a deep violet shade of blue.
Then the Emperor did the strangers the honor of recording the wavelengths of their light. He motioned for his scribes to bring a diffraction grating, which is a finely-lined window. The grating bends any beam of light passing through it by an angle proportional to the light's wavelength, so that by noting the angle the scribes could reckon each dervish's wavelength.
The wavelength of the red light was 7 millionths of a bone, that of the green light was 5 millionths, and that of the blue was 4 millionths. A bone is the width at the first knuckle of the little finger on Emperor's right hand. The barbarians speak of the Emperor's fingerwidth as 1.619 centimeters but this is bad manners and when foreigners talk this way a polite person pretends not to notice.
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Copyright © 2002 Leonard Cottrell. All rights reserved.
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