Someone would have manned the site, watching for contiguous warning signals to be lit. The Largo Law site may have been looking towards the Lomonds or Kellie Law for signals. The word 'Lomond' means beacon or blaze of light. Sometimes codes (eg one, two or three fires) may have been used to show the level of danger or the type of action required. The beacons may also have had a role in aiding navigation at sea. Of course, such beacons were dependent upon fine weather for visibility.
More on beacons / bonfires tomorrow.