452 
Will-o’-the-Wisp : a Confession . 
[August, 
spirit. Mr. Sheppard informed Dr. Kirby that when travel- 
ling one night from Stamford to Grantham, on the top of a 
stage-coach, he observed “ for more than ten minutes a very 
large Ignis fatuus in the low marshy grounds, which had the 
same motions as a Tipula } flying upwards and downwards, 
backwards and forwards, sometimes as settled, and some- 
times as hovering in the air.’ 5 It is remarked that in this 
case the wind was very high, so that a vapour would have 
been carried forward in a straight line, which was not the 
case. We are well aware that the insedt- theory is not free 
from difficulties. Thus the question at once arises, Why 
is this phenomenon so rare ? It is also to be asked 
whether the light given off by insedts is sufficiently strong 
to be visible at such distances as the Wisp is said to have 
been ? 
The orthodox theory at the present day — that of sponta- 
neously inflammable gases, hydrogen phosphide, marsh-gas, 
and possibly hydrocarbons given off by decomposing animal 
or vegetable matter, is open to even more formidable objec- 
tions. The presence of the spontaneously inflammable 
variety of hydrogen phosphide has never yet, we believe, 
been analytically demonstrated among the gaseous matter 
given off from marshes, pools, and cemeteries'. 
In Brande’s “ Dictionary of Science, Literature, and Art ” 
(ii., p. 191) the Wisp is ascribed to “ the issue of marsh-gas 
from the earth. This gas, being ignited either accidentally 
or intentionally, continues to burn with a flame sufficiently 
luminous to be well seen at night.” The writer admits, at 
the same time, that no natural production of spontaneously 
inflammable gas has ever been observed. Dr. Phipson gets 
over the difficulty of ignition by assuming that the gas given 
off consists of marsh-gas through which a small proportion 
of hydrogen phosphide is diffused. But an emission of in- 
flammable gases from the earth or the water, however ignited 
and however composed, will not account for the phenomena 
in the majority of cases on record. In proof of this let 
anyone perform the simple experiment of stirring up the 
mud at the bottom of a dirty ditch or pond, and ignite the 
marsh-gas given off by means, say, of a piece of taper fixed 
at the end of a fishing-rod. The gas will burn immediately 
over the surface of the ditch or swamp, but the flame will 
not travel away for considerable distances, overleaping 
hedges, stiles, trees, or buildings, or playing over thistles. 
Further, it is found that the Wisp is most common in calm, 
fine weather, when the barometer is high. But gases pent 
up in the soil, in marshes, &c., will be most readily evolved 
