ten thousand inhabitants; each of the subdivisions had an officer in authority who was answerable to the chief officer of the larger group of which his division formed a part, until the supreme authority was reached. As may be supposed, the larger divisions were under the direction and control of the nobles, the provinces of ten thousand being governed by the Inca nobility, who had command over the curacas and other territorial officers of his district. The subjects of the Inca could not even choose their life partners; matrimony was obligatory and, as its results affected the well-being of the state, the Inca maintained the right to govern in this as in all other matters. In the royal family, the ceremony was performed by the emperor himself, though in marriages of lesser importance his officers discharged this formality, appointing a day for a general ceremony, when all the young men of from twenty to twenty-five and girls of from eighteen to twenty presented themselves in a row, the men in front; after the wedding, the young people took possession of the houses which their community was obliged to build for them, the furniture being supplied by their family. No one could marry outside of his or her _parcialidad_, or township, and, as it was obligatory to wear the dress of one’s forefathers and not to move from any town to another without leave from the authorities, it may readily be understood that the costumes worn in the various sections of Peru were as distinctive of class and locality as is the Scotch tartan. The custom still remains in the sierra, and the effect is most picturesque. [Illustration: PRINCIPAL HALL OF THE INCA OBSERVATORY. INTI-HUATANA.]