MEASURING A FLASH OF LIGHTNING.

Wairarapa Daily Times, Volume XV, Issue 4320, 16 January 1893, Page 2

MEASURING A FLASH OF LIGHTNING.

11 Did you diameter of a lightning flash measured f a sked a geologist. " Well, bero is the case which once enclosed a flash of lightning, fitting it exactly, so that yea can see how big it was. This ia called a < fulgurite,' or ' lightning hole," and the material it is made of is glass. I will tell you how it was manufactured, though it took only a fraction of a second to turn it out, When a bolt of ligbtnihg strikes a a bed of sand it plunges downward into the sand for a distance, loss or greater, transforming simultaneously into glass the silecia in the material through which it passes. Thus, by its great heat, it forms at once aglasß tube of precisely its own size. Now and then such a tube is found and dug up. Fulguritesjjave been followed into thojandjjy excavation for nearly thlrtyM, They vary in interior diameteK from tho size of a quill to three inohj's pr more, according to the bore QT the flash. But fulgurites are not alorWoduced in sand; they are found alk in solid rocks, though'very naturallyW slight depth and frequently existingVnorely as a thin glassy coating oft tho surface; Such fulgurites occur in astonishing abundance on tho summit of little Ararat, in" Armenia. The rock is soft and so porous thai blocks, a foot long can be obtained, perforated in all directions by little ■ tubos filled with bottled green glass , I formed from tho fed roolV'-BMjrj toßevib?! '■''-■ A