Argus Charley airplane spotter beat course cover defend defending do fire patrolman fire warden fireguard forward observer go over guard guarding keep guard keep vigil keep watch lookout lookout man measure mount guard night watchman overpass pass over pass through patroller patrolman perambulate peregrinate pererrate picket ply police protect protecting protection range range over reconnoiter rounds roundsman safeguarding scour scour the country scout sentinel sentry spotter stand guard stand sentinel sweep track transit travel over travel through traverse vedette vigilance voyage watch watch over watcher watchfulness watchkeeper watchman