Page:Popular Science Monthly Volume 30.djvu/552

532 Passing by, for lack of space, the interesting accounts given by Darwin and Fiedler of fulgurites found at Maldonado, near the mouth of the La Plata, in South America, and in a vineyard on the right bank of the river Elbe, and simply noting the finding of similar tubes at Northfield Farms, Massachusetts, in 1861, we will mention the next recorded occurrence at Macclesfield, England, which, like that of Cumberland, is remarkable on account of the length of the tube found. This is described as three fourths of an inch in diameter at its upper end, and tapering gradually throughout its length to within three or four feet of its lower end, where it assumed a slanting direction, and then divided into several filaments or branches, and became dispersed and obliterated in the soft, spongy soil. This fulgurite was traced to a depth of twenty-two feet in a straight line, and gives us a good illustration of the immense heat and power of penetration of an electric discharge.

The occurrence described by Roemer, of twenty-five sets of fulgurite tubes, within a space of one hundred by two hundred yards in the great sand-flats of Starczynow in Poland, is, I believe, the most remarkable on record. The sand in this case was a very pure quartz-sand with a few pebbles of rolled flint ("Feuerstein").

The tubes were found with their upper ends exposed, owing to the blowing away of the loose sand, and varied in size from the thickness of one's arm to that of a wooden knitting-needle, while the thickness of the tube-wall varied from one to two millimetres, rarely more.

An article by the present writer gives a detailed description of fulgurites from Santa Rosa Island, Florida; Sumter, South Carolina; and Union Grove, Illinois, now in the collections of the National Museum.

Those from Santa Rosa were formed by the lightning striking a small pine-tree, and thence descending to the ground, where, at a distance of about forty feet from the trunk it formed a tube, which occurred as a crooked, irregular line along the surface. This was nearly pure glass, grayish in color, translucent, and very free from corrugations, though in some cases completely collapsed. The small fragments of the tube from Sumter, South Carolina, were found while digging a well at a depth of twenty feet below the surface. The tube-walls were very thick and strong, brownish and opaque. They lacked the corrugations, but had, externally, rather the knotted appearance compared by Gümbel to that of stag's horns. The great amount of material received from Union Grove, Illinois, shows this to be