During the month of July last we had the pleasure of witnessing this very curious phenomenon, in the marshy grounds between Hertford and Stevenage, when on the mail, coming from London northward. The day had been dense and sultry, and toward evening a stratum of vapour hovered over the marshes of the valley. On the right two ignes fatui started up suddenly, and at some distance apart; the appearance was altogether that of a solid ignited nucleus, diffusing brilliant radii around it. Their locality, as far as could be determined, seemed to be clumps of rushes. At one period there appeared to be a flitting flickering motion, somewhat resembling that of a hovering insect; but this was not continued. The phenomenon lasted several minutes, and both were suddenly extinguished, the one after the other.
It seemed to us difficult to conceive of electricity being presented under the attendant phenomenon with which these were accompanied, and the entire features were more analogous to those of an insect powerfully illuminated; but whether some insect allied to the tribe termed Gryllus gryllotalpa, or mole cricket, has the power, under peculiar circumstances, as the Rev. Dr. Sutton has conjectured, of evolving light, seems not altogether determined: this phenomenon might be adduced to plead in its favour, thus the scolopendra electrica is occasionally luminous, when excited.
We find that a gentleman observed a similar phenomenon to that described, in low marshy ground, after a sultry day and a dense evening fog; it had also to his vision all the appearance of a solid ignited body. We have also witnessed a lambent flame gliding on the surface of a stagnant lake, but are of opinion this last is altogether distinct from the other, and depends on different principles.
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