66 METEOROLOGICAL 
Weissenborn, in 1818, where the light travelled 
over a distance of half a mile in less than a second. 
(Mag. of Nat. Hist. n.s. 1. 053.) 
From these facts, it appears probable to modern 
philosophers, that there are two kinds of ignes 
fatui, the one referable to spontaneously inflam- 
mable gas, the other to luminous insects. 
If phosphuretted hydrogen, or any other spon- 
taneously combustible gas or liquid, caught fire 
upon a marsh where carburetted hydrogen (marsh 
gas) 1s constantly evolved, the latter would in- 
flame also.* 
In the valley of Gorbitz, Mr. Blesson discovered 
a light emanating from marshy ground. Remain- 
ing for some days near the place, in order to study 
the phenomenon as closely as possible, he found 
it was owing to an ignited gas, the faint flame of 
which was invisible during the day, but became 
gradually visible in the evening. ‘The gas appears 
to have been carburetted hydrogen, or marsh gas. 
As he approached it, the flame receded, but he 
eventually succeeded in lighting a piece of paper 
by it. 
According to some authors, Will-o’-the-Wisp 
may be seen at all seasons of the year; but a great 
* At Wigmore, in Herefordshire, and other places in England, 
carburetted hydrogen used to be so abundant in the ground that 
it was employed for lighting and cooking in the houses, as we 
learn from travellers is a common practice in China, 
