No. 136: JUL-AUG 2001
A remarkable phenomenon was seen near this town [Harlech] 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 sunset, 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 other forts of grain were destroyed, but also the vegetables in the gardens, for it had so noxious a smell that everything perished where it diffused its baleful infuence. Its effect 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 rising at the same place, nor did it stop its course either by rain or storms. It was sometimes visible by day, but it was very remarkable that it never did any damage except in the night. The flames were in no way violent, but its continuance at last consumed everything that opposed it.
Those few scientists who have mused over this curious old account have concluded that the "fiery exhalations" resulted from the spontaneous ignition of marsh gas; that is, the flames were will-o'-the-wisps, albeit relatively powerful ones. Will-o'-the-wisp theory states that marsh gas (mostly methane) also contains phosphane and traces of diphosphane (P2H4). The latter gas reacts spontaneously with air and ignites the methane, creating weak blue flames.
The New Scientist article mentioned a parallel modern occurrence that is new to us and worth recording here. In 1997, a dramatic series of spontaneous fires burst forth in the town of Moirans-en-Montagne located in the Jura mountains of France. No details were presented although emanations of natural gas were suspected.
(Pentecost, Allan; "From the Deep," New Scientist, p. 89, August 26, 2000.)
Comments. We classify will-o'-the-wisps along with other nocturnal lights in GLN1 in Lightning, Auroras...., where one can find doubts about the standard explanation of these phenomena that was presented above.
The region of Wales that experienced the fiery exhalations in 1693-1694 also saw another "flap" of less-destructive luminous phenomena in 1904-1905. These were the Egryn Lights, which were concentrated along the active Mochras Fault and might, therefore, have been earthquake lights, which have been officially named but not authoritatively explained.
Even more interesting (to us) than the possible earthquake lights is the association of the Egryn Lights with the great Welsh religious revival of 19041905. A great variety of luminous phenomena were observed by many of the worshippers caught up in the fervor. In particular, the lights seemed to attend the preachings of a Mary Jones, who often held forth at the Egryn Chapel that gave the lights their name. (For details on the Welsh revival and its accompanying luminous phenomena -- psychic or geophysical, see our photocopied report "Psychological Aspects of the Welsh Revival." $7.00p.
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