156 



E. PvTJTLEX OlS BOTJTEILLENSTETN'. 



In concluding this short paper, I would express my sincere thanks 

 to Prof. Judd for the trouble he has taken in preparing the sections 

 upon which these observations have been mainly based. 



-EXPLANATION OF PLATE HI. 



Fig. 1. Globule of brownish fulgurite glass detached from the surface of a speci- 

 men of hornblende-gneiss. Summit of the Dom du Goute, Chain of 

 Mont Blanc The globule shows a blow-hole at y, and its point of 

 attachment at ^ . X 25, 



2. Fragment of brownish fulgurite glass broken from a bubble. It simply 



shows conchoidal fractures and some gas-bubbles. No trace of 

 crystallization is yisible in it . X 120. 



3. Fulgurite on hornblende-gneiss. The group of glass globules at z show 



a somewhat radiate distribution, and some of them are connected by 

 a slightly vitrified trail. Natural size. 



4. Glass enclosure containing numerous gas-bubbles occurring in fulgurite 



glass, broken from a bubble . x250. 



5. Fulgiu'ite adhering to surface of hornblende-gneiss. At b two gas- 



bubbles are seen in the fulgurite glass which incrusts the sm-face of 

 the rock, but does not penetrate. The dark opaque part of the rock 

 immediately imderlying the fulgurite appears white when viewed by 

 reflected light. Thin section, X 120. 

 All these specimens are from the same locality. Figs. 1, 2, 4, and 5 are 

 represented as seen under the microscope by ordinary transmitted Hght. 



DisciJssio]!r. 



The Presidei^t said that Mr. Eceles, in some of his Alpine ascents, 

 had made a number of observations on the action of lightning on 

 rocks, and had pointed out to himself an example of it on Monte 

 Leone. 



Prof. BoTD Dawkests had not seen any evidence from the paper 

 that the fusion in these cases was due to lightning. He referred to 

 the vitrification of rocks produced in vitrified forts and by beacons. 



Prof. Judd referred to the discovery of fulgurite by Abich on the 

 Little Ararat, and to the existence of other glasses without crystal- 

 lites in Siberia, Iceland, and I^ew Zealand. 



The AuTHOE, in reply to Prof. Boyd Dawkins, explained that the 

 rock could not, from its situation, have been fused by artificial 

 means. 



