Two postal services were available under the empire, one public and one private. The Cursus publicus, founded by Augustus, carried the mail of officials by relay throughout the Roman road system. The vehicle for carrying mail was a cisium with a box, but for special delivery, a horse and rider was faster. One reference states that a relay of horses could carry a letter 800 km in 24 hours. The postman wore a characteristic leather hat, the petanus. The postal service was a somewhat dangerous occupation, as postmen were a target for bandits and enemies of Rome. Private mail of the well-to-do was carried by tabellarii, an organization of slaves available for a price.