1832-3.] SAND TUBES FORMED BY LIGHTNING. 71 



At Paris, M. Hachette and M. Beudant* succeeded in 

 making tubes, in most respects similar to these fulgurites, 

 by passing very strong shocks of galvanism through finely- 

 powdered glass : when salt was added, so as to increase 

 its fusibility, the tubes were larger in every dimension. 

 They failed both with powdered felspar and quartz. One 

 tube, formed with pounded glass, was very nearly an inch 

 long, namely, '982, and had an internal diameter of '019 

 of an inch. When we hear that the strongest battery in 

 Paris was used, and that its power on a substance of such 

 easy fusibility as glass was to form tubes so diminutive, 

 we must feel greatly astonished at the force of a shock of 

 lightning, which, striking the sand in several places, has 

 formed cylinders, in one instance of at least thirty feet 

 long, and having an internal bore, where not compressed, 

 of full an inch and a half; and this in a material so 

 extraordinary refractory as quartz ! 



The tubes, as I have already remarked, enter the sand 

 nearly in a vertical direction. One, however, which was 

 less regular than the others, deviated from a right line, 

 at the most considerable bend, to the amount of thirty-three 

 degrees. Fromlthis same tube, two small branches, about 

 a foot apart, were sent off; one pointed downwards, and 

 the other upwards. This latter case is remarkable, as 

 the electric fluid must have turned back at the acute 

 angle of 26°, to the line of its main course. Besides 

 the four tubes which I found vertical, and traced beneath 

 the surface, there were several other groups of fragments, 

 the original sites of which without doubt were near. All 

 occurred in a level area of shifting sand, sixty yards 

 by twenty, situated among some high sand-nillocks, 

 and at the distance of about half a mile from a chain 

 of hills four or five hundred feet in height. The most 

 remarkable circumstance, as it appears to me, in this 

 case as well as in that of Drigg, and in one described 

 by M. Ribbentrop in Germany, is the number of tubes 

 found within such limited spaces. At Drigg, within an 

 area of fifteen yards, three were observed, and the same 

 number occurred in Germany. In the case which I 

 have described, certainly more than four existed within 

 the space of the sixty by twenty yards. As it does not 

 appear probable that the tubes are produced by successive 

 distinct shocks, we must believe that the lightning, 



* " Annales de Chimie et de Physique," torn, xxxvii., p. 319. 



