The site of a night watch beacon at Poolvaaish dating to 1627 (and probably earlier). It is commemorated by the name Cronk y Watch (on the 1957 Ordnance Survey 6 inch map). It shown as 'Polbash' on a map with an official document dated 1627. The watch system, which apparently derives from the Norwegian period, was founded on a chain of vantage points around the island, two at least in every parish, upon which beacons were prepared. There is written evidence, as early as the 1490s, that every parish kept both Day and Night watches.