Page:Popular Science Monthly Volume 30.djvu/550

530 would far exceed the limits of this paper. It is my purpose, therefore, to call attention only to those peculiarly interesting, though usually quite harmless, effects produced by the lightning striking in loose sand; though, before closing, I shall allude to the closely allied phenomena resulting from similar discharges upon solid rock. In the sand, as is well known, the usual result produced is that of fusion whereby a frail, glassy tube of variable diameter and length is produced, the interior of which is a true amorphous glass, quite smooth, while exteriorly it is roughly granular and greatly corrugated. Such are called fulgurites or fulmination-tubes in English, while, to the German and French, they are known as Blitzröhren and tubes fulminaires respectively.

So far as can be learned from available literature, the earliest description to be made of these peculiar objects was that of Pastor David Hermann in 1711. According to Gilbert, this gentleman, as early as 1706 and 1707, dug from a sand-hill in Massel, Silesia, fulgurites some twenty feet in length, which he very fully described in his work on Massel and its curiosities.

Hermann's account is curious and full of interest, as his statements concerning the origin of the tubes were the purest guess-work, and his views regarding them wild in the extreme. He designated them by the name "Osteocolla," and proposed to use them for medicinal purposes, as will be noted later.

The earliest account of an occurrence of this kind, where the fusion was indubitably proved to be due to lightning, is that of Mr. Withering, in the "Transactions of the Philosophical Society of London for 1790." In the narrative as there given, a man, who had taken refuge beneath a tree at Aylesford, England, during a thunder-storm, was instantly killed and his clothing set fire from a flash of lightning, which first struck the upper portion of the tree and thence passed downward toward the ground. A portion of the electric fluid, after leaving the man's body, passed down a walking-stick held in his hand and thence to the ground, where it made a hole some two and a half inches in diameter. The first ten inches of this bole presented nothing worthy of remark; at this point, however, the fluid was found to have followed along for some eight inches the root of a tree which presented itself, and which, aside from a slight superficial blackening, was unharmed. Some closely adjacent quartz-pebbles did not, however, escape so easily, but were found with their corners and angles very considerably rounded by fusion. The hole was traced only to a depth of about eighteen inches, and no real tube is mentioned as having been discovered.

The next account which we have to notice is that given by Dr. Fiedler, who describes in detail the finding of fulgurites by Dr. Hentzen and others in the great sand-wastes of Paderborn,