378 PROCEEDINGS OF SECTION ©. 
beads on the face of some slaty hornblende on the Dome de Gouté, 
obviously produced by the action of lightning. 
The directness of the evidence as to the origin of fulgurites is, 
perhaps, best illustrated in the account given by Withering® in 
1790, published in the Phil. Trans. of the Royal Society. On 
3rd September, 1789, a tree was struck by lightning, and a man 
who had taken refuge thereunder was killed. At the point of his 
walking-stick a perforation, 24 in. in diameter and 5 in. in depth, 
marked the place where the flash entered the ground, On 
digging, the soil was observed to be blackened for 10 in. more ; 
2 in. deeper again melted quartzose appeared, and continued in a 
sloping direction for 18 in. the fused material having run down 
the tube formed. 
F. Humboldt’ obtained some fulgurites in Mexico in about 
1803, from the summit of a trachyte peak, about 15,000 feet above 
sea-level. The fused mass on the walls of the fulgurite had 
apparently overflowed. About the same year articles appeared 
in Moll’s Annalen on “ Kieselsinter ;” one by Moll" himself, and 
the other by Emmerling."" In 1805 Hentzen” found a large num- 
ber of fulgurites in the Senne Heath at Paderborn, Westphalia, 
to which he gave the name lightning-tubes (Blitzrohren), thus 
identifying, by name, these structures with their cause. 
Hagen” reported i in 1823 that his son had actually witnessed 
the striking of a birch by lightning. On digging beneath it the 
fused tubes were found. 
In 1828 Beudant,” together with Hachette and Savart, made 
several small fulgurites artificially with powdered glass, and also 
with a mixture of powdered glass and salt, the latter being the 
more easily fused. The glass gave a tube 25 mm. in length, and 
with end diameters of about 3 mm. and 14 mm., the interior 
diameter being about} mm. With salt added, a tube 30 mm. 
was obtained of an average diameter of 44 mm., and an interier 
diameter of 2 mm. These tubes were produced by the most 
powerful electrical apparatus then available. 
Evidently there can be no doubt as to the origin of fulgurites. 
It may be mentioned that the suggestion that these siliceous tubes 
are formed by other process than electric fusion, since roots are 
sometimes found in their interior, was disposed of by Fiedler***”® 
at the beginning of the century, and the matter does not now 
require serious discussion. 
The occurrence of large numbers of fulgurites within an area of 
small radius led Darwin* to believe that they were often produced, 
not by lightning shocks at different times, but altogether. He 
concludes that, shortly before entering the ground, the lightning 
divides into separate branches, each forming a a fulgurite. Probably 
they are so formed—that is to say, more than one is often formed 
at a single flash—that the photographs of flashes lend a strong 
