HEMERODROMI, compounded of ἡμέρα, day, and δρομος, course, amongst the ancients, were sentinels or guards appointed for the security and preservation of cities and other places. They went out of the city every morning as soon as the gates were opened, and kept all day patrolling round the place; sometimes also making excursions into the country, to see that there were no enemies lying in wait to surprise them.