1886.] PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 85 



Like those from Santa Eosa, tbey were formed by the lightning striking? 

 in loose sand, bnt while the inner surface was ghized the outer was 

 covered with a rough coat of grains of siliceous sand, iron oxides, and 

 organic matter, rendering the tube entirely opaque instead of trans- 

 lucent, as in the case already mentioned. The surfaces were also very 

 deeply corrugated, as will be noticed in the plate. With considerable 

 difQculty there were prepared some cross-sections of these, which were 

 submitted to microscoi)ic examination. The tube wall was fonnd to be 

 1 or 2 millimeters in thickness, the inner portion of which consisted of 

 a true amophous glass, colorless or stained brownish in streaks, and in- 

 closing innumerable bubbles and a few black opaque grains, which are 

 probably iron oxides. Fully three-fourths of the tube wall is glass, 

 with a narrow margin of sand grains adhering to the outer portion by 

 means of the glassy cement. No such radial arrangement of elongate 

 bubbles as described by Wichmann and Gumbel* could be seen, neither 

 could I find such arrangement in a cross section prepared from other 

 fulgurites received from Sumter, S. C.t The sand in which they were 

 found was largely siliceous, with a few feldspathic grains and iron oxides, 

 together with a little organic matter. The following in regard to the 

 mode of occurrence of the specimen is from Mr. Abbott's letter: 



"The locality is the top of a sand knoll, and includes in area a spot 

 about 50 feet square. Besides the tubes there was found an irregular 

 mass, fused together, which would weigh several ounces. This mass 

 had no connection w^th anything else, for it had no broken edges. 

 The largest tube was about 3 J inches in diameter, bnt the glassy lining 

 was so thin and fragile that no sections could be removed. The next 

 in size was about 2 inches across. This was convoluted and irregular 

 in section, giving it an appearance not unlike the rough bark of a tree. 



* * * This fulgurite was traced into the sand 7 feet, increasing 

 somewhat in size from above doimiicard. In common with all others 

 found, its course was nearly straight and vertical. On this and several 

 other of the specimens were found small flat branches running horizon- 

 tally for several feet. These were about one-fourth of an inch wide and 

 half as thick, the greater diameter being horizontal, and the longitudinal 

 hole being quite small and entirely absent toward the end, which ter- 

 minated abrui)tly. Of a different nature was a short branch on the 

 specimen, about the size and shape of a man's thumb; this was inclined 

 slightly upward. A number of other fulgurites were found ranging in 

 diameter down to a quarter of an inch, bnt having the same general 

 features, except that they were more regular and cylindrical in section. 



* * * One peculiar fulgurite was found having bulb-like enlarge- 



* Op. cit., p. 852 aud 648. 



tThe gift of Mr. C. T. Masou. These last were very thick and strong, and were 

 stated by Mr. Mason to have been found while digging a well, at a depth of 20 feet 

 below the surface. The thickness of the glassy lining was in one case nearly 2 ■"■". 

 These lacked the wing-like corrugations shown in the plate, but bad more the knotted 

 appearance comiiared by Gumbel to that of stag-horns. 



