Harloch, or Harleich, in North Wales, is 223 miles from London, on the sea-coast, near the north-west point of the county. It is naturally strong, a garrison being kept here for the security of the coast. Its castle lies now in ruins. The town, though a corporation and governed by a mayor, makes but a very mean appearance. The market is on Saturdays; and there are four fairs, on the Thursday after Trinity Sunday, June 13, August 21, and December 11. Near it is a cataract of the Rhaids-du, which rushes down a mountain for 100 yards, and then forms a cataract whose water forms part of an elliptical curve, to a pool forty feet below. A remarkable phenomenon was seen near this town in the year 1694, and it continued about the space of eight months. It was a livid vapour, or fiery exhalation, which seemed to arise from the sea on the borders of Caernarvonshire. It made its first appearance on the side of a bay, a little after sun set, and from thence spread itself in the most gradual manner, until it had set all the houses in the neighbourhood on fire. Not only the ricks of hay, corn, and all other sorts of grain, were destroyed, but also the vegetables in the gardens; for it had so noxious a smell, that every thing perished where it diffused its baleful influence. Its effects were severely felt by the cattle, to whom it communicated a contagious distemper, by which many of them died. It made its appearance regularly every night, always arising at the same place; nor did it stop its course either by rain or storms. It was sometime visible in the day; but it was very remarkable that it never did any damage except in the night. The flames were no way violent, but its continuance at last consumed every thing that opposed it.
Source: The Universal British Directory of Trade, Commerce, and Manufacture 1791. Vol. 5.