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The Museum Gazette 



ON THE EFFECTS OF LIGHTNING. 

 Formation of Fulgurites. 

 We have not in the Haslemere Museum any specimen of 

 a Fulgurite, and shall be greatly obliged to any friend who 

 may put us in the way of obtaining one or more. They are 

 educational in high degree, as giving proof of the intense 

 heat which attends the lightning flash, and also affording illus- 

 tration of the principles which underlie the making of glass 

 A Fulgurite is a conical tube of rough glass made in sand 

 by the passage of lightning downwards into the earth. The 

 following is M. Flammarion's description of them. 



" Lightning is truly the most venerable of glass-makers. Long 

 before the most remote peoples of antiquity appeared, whose glass- 

 wares, encrusted with marvellous iridescent tones by the passing 

 of the centuries, are unearthed by scientific excavations, and displayed 

 in national collections ; long before man could have learnt to make 

 use of the resources of Nature, lightning, burrowing in the sand, 

 there fashioned tubes of glass that hold the hues of the opal, and 

 are called fulgurites. 



"The ancients seem to have known of these fulgurite tubes, but 

 we owe the first precise description and the first specimen of these 

 extraordinary vitrifactions to Hermann, a pastor at Masse], in Silesia. 

 His fulgurite, found in 1711, is in the Dresden Museum. Since this 

 discovery, fulgurites have often been sought for and found. The 

 tubes, contracted at one end and ending in a point, are to be seen 

 in sandy soils. Their diameter varies from 1 to 90 millimetres, and 

 the thickness of their sides from half to 24 millimetres. Vitrified 

 inside, they are covered outside with grains of sand, agglutinated, 

 and apparently rounded, as if they had been subjected to a beginning 

 of fusion. The colour depends upon the nature of the sand in which 

 they have been formed. Where the sand is ferruginous the fulgurite 

 takes a yellowish hue, but if the sand is very clean, it is almost 

 colourless, or even white. As a rule the fulgurites penetrate the 

 ground vertically ; nevertheless, they have been found in an oblique 

 position. At times, also, they are sinuous, twisted, or even zig-zag, 

 if they have met with pebbles of considerable size. 



" It is not uncommon for the fulgurite tube to divide in two or three 

 branches, each of which gives birth to little lateral branches of 2 or 

 3 centimetres long, and ending in points.' 5 



Sometimes fulgurite-funnels are formed, not in sand, but in 



