explained, is obvious. These were probably electrical phenomena;
certainly not explosions of phosphuretted hydrogen, as has been
suggested by some, which must necessarily have been momentary. But that
the _ignis fatuus_ mentioned by Derham as having been seen by himself,
and which he describes as flitting about a thistle, was, though he seems
of a different opinion, no other than some luminous insect, I have
little doubt. Mr Sheppard informs me that, travelling one night between
Stamford and Grantham on the top of the stage, he observed for more than
ten minutes a very large _ignis fatuus_ in the low marshy grounds, which
had every appearance of being an insect. The wind was very high:
consequently, had it been a vapour it must have been carried forward in
a direct line; but this was not the case. It had the same motion as a
_Tipula_, flying upwards and downwards, backwards and forwards,
sometimes appearing as settled, and sometimes as hovering in the air.
Whatever be the true nature of these meteors, of which so much is said
and so little known, it is singular how few modern instances of their
having been observed are on record. Dr Darwin declares, that though in
the course of a long life he had been out in the night, and in the
places where they are said to appear, times without number, he had never
seen anything of the kind; and from the silence of other philosophers of
our own times, it should seem that their experience is similar."

A paper by Mr R Chambers on the subject adduces the additional
testimony of facts observed by good naturalists, as Dickson and
Curtis the eminent botanists, and Stothard the painter and entomologist,
by his own father Mr A. Chambers, and by Joseph Simpson, a fisherman
living near Boston, all of which strongly corroborate the probability
that some, at least, of the _ignes fatui_ are produced by luminous
insects.[154] Mr Main narrates the case of a farmer who stated
that he had pursued a Will-o'-the-wisp, and coming up with it had
knocked it down, when it proved to be an insect "exactly like a
Maggy-long-legs"--that is, the common Crane-fly (_Tipula oleracea_), the
very insect with which Mr Sheppard had compared the motions of the
luminous flame observed by him.[155] Mr Spence argues that while gaseous
emanations may be a cause of stationary _ignes fatui_, the same cause
will not explain those which flit along from place to place; and that
these are probably luminous insects, however rar