It appears on the 1898 re-survey of the OS six-inch map, marked plainly as 'Sun Dial', which is itself a small curiosity: the cartographers considered it worth recording, suggesting it was a recognised feature of the landscape rather than a garden ornament that happened to face the right way.

The most plausible explanation for its presence is the former coastguard station that once occupied the ground to the south-west. Coastguard stations along the Irish Atlantic coast were functional, disciplined places, and accurate timekeeping was a practical necessity rather than an affectation. A fixed sundial on an elevated position, with a clear view northward over the bay, would have served that purpose well. No visible trace of the sundial survives today, leaving only the mapped name as evidence that it ever existed. The rise itself remains, and the view over Cleggan Bay presumably does too, but whatever instrument once stood there, whether a stone plinth, a pedestal, or something more substantial, has long since gone.