King of Sarra, in the land of Tartary; the model of all royal virtues. His wife was Elfeta; his two sons, Algarsife and Cambalo; and his daughter, Canacë. On her birthday (October 15th) the King of Arabia and India sent Cambuscan a “steed of brass, which, between sunrise and sunset, would carry its rider to any spot on the earth.” All that was required was to whisper the name of the place in the horse's ear, mount upon his back, and turn a pin set in his ear. When the rider had arrived at the place required, he had to turn another pin, and the horse instantly descended, and, with another screw of the pin, vanished till it was again required. This story is told by Chaucer in the Squire's Tale, but was never finished. Milton ( Il Penseroso ) accents the word Cambus'-can.
Him that left half-told The story of Cambuscan bold.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894