Page:Popular Science Monthly Volume 30.djvu/553

bly the most extensive find of fulgurites yet noted in this country. The locality where they occurred is the top of a sand-hill some fifty feet square. Several sets or pairs of tubes were found here, but a few inches apart, together with several small, irregular masses of fused material, the largest of which weighed several ounces. The largest tube found was about three and a half inches in diameter, but was too frail to remove. The accompanying plate shows the characteristic forms.

Fulgurite Tubes (natural size). (Reproduced from Proceedings of the United States National Museum, vol. ix, 1886.) Fig. 1, portion of tube, common form; Fig. 2, tube with bulb-like enlargement; Fig. 3, cross-section of tube, characteristic form; Fig. 4, holes fused by lightning in sheet-copper, and resembling fulgurite tubes in outline.

One of these was traced into the sand for a distance of about seven feet, and was found to increase in size slightly from above downward. They were frequently branched, and often sent out small, nearly flat horizontal branches or shoots, about one quarter of an inch wide, and