The expression “fossil lightning” may seem somewhat paradoxical, but it is here employed in a figurative sense to designate a condition of things which we have good modern evidence to prove to have been the result of the lightning's flash, myriads of ages gone by. Of late years vitrified sand-tubes have been discovered in Cumberland, in Prussia, South America, Natal, and other places; and these have been very clearly made out as having been directly caused by lightning, and hence they have been called by mineralogists “Fulminary tubes” or Fulgurites. All these would appear, so far as we can ascertain, to have been formed at comparatively a very recent period, and hardly, therefore, deserving of the appellation of “fossil lightning.” Nevertheless, as I have come across some examples of such bodies on the surface of the flagstones which form our pavements, and of the antiquity of which there cannot be any doubt whatever, I have no hesitation in making use of the term which heads this chapter.