Possible Origin of the Ignis Fatnus. 553 



from the foot of the hillock on which the house where I was 

 is standing. Through the first third of the meadows there runs 

 a winding rivulet, of the breadth of 7 or 8 feet, which then 

 turns off" into an artificial bed, whilst the old bed continues 

 in the direction of the meadows, which are bounded on one 

 side by a range of brush-wood, on the other by cultivated 

 grounds, with marshy dells here and there. My intimate 

 acquaintance with the locality, together with the bright moon- 

 shine, enabled me to discern every object round the meadow- 

 ground sufficiently well to judge of the position and direction 

 of the luminous phenomena, the display of which I saw, as 

 soon as I had posted myself at the window. I perceived a 

 number of reddish-yellow flames in different parts of the 

 expanse of almost level ground. I descried, perhaps, no 

 more than six at a time; but dying away, and appearing in 

 other places so rapidly, that it was impossible to count them ; 

 but I should say, on a rough estimation, that there were about 

 20 or 25 within a second. Some were small, or burned dimly ; 

 others flashed with a bright flame, in a direction almost pa- 

 rallel with the ground, and coinciding with that of the wind, 

 which was rather brisk. After having for some time looked 

 with amazement at this brilliant scene as a whole, I tried to 

 study its details ; and soon found that the flames which were 

 nearest originated in a quagmire, whose position I knew ex- 

 actly, by a solitary cluster of willows; and I could trace a 

 succession of flashes from that spot to a certain point of the 

 margin of the wood, across the rivulet and meadow. The 

 distance of the two points from each other was more than 

 half a mile, and the flames travelled over it perhaps in less 

 than a second. The first flash was not always observed in 

 the immediate neighbourhood of the quagmire ; but the suc- 

 cession of flames lay always in the same straight line, and in 

 the direction of the wind ; whilst other sets were, though not 

 with the same distinctness, observed in the more distant parts 

 of the meadow-ground. After about an hour, a bank of mist 

 began to overspread the meadow ; but I saw the light still 

 glimmering through it, whilst I dressed myself to examine the 

 the phenomenon in its laboratory. However, when I reached 

 the meadow, the atmospheric conditions which gave rise to 

 the Ignes Fatui had ceased to exist. From what I saw, I 

 must judge that the Ignes Fatui are owing to the causes given 

 by Volta; viz., that the phosphoric hydrogen exhaled by cer- 

 tain swamps is kindled by coming into contact with the atmo- 

 spheric air ; but, as the hydrogen is not saturated with phospho- 

 rus, the greater proportion of the latter being precipitated, in 

 passing through the water, as red oxide of phosphorus, there 

 Vol. I. — No. 10. n. s. s s 



