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Professor Miller exhibited two new forms of heliotrope, explaining 

 at the same time the difficulties in signalling, which they were in- 

 tended to overcome, commenting upon the relative merits of those 

 invented by Gauss, Steinheil, and others, and explaining the spe- 

 cial advantages of the two which he exhibited. 



Professor Miller also communicated a Supplement to the Crystal- 

 jgraphic method of Grassmann. 



Mr. G. F. Browne, St. Catherine's College, communicated some 

 Notes upon some Ice-caves explored during the summer of 1865. 

 Two of these he had visited during the previous summer, and he 

 found that there was a somewhat greater quantity of snow in the 

 caverns than there had formerly been. In the first cave he again 

 examined a pit in the ice about 70 feet deep, but, owing to the dan- 

 gerous condition of the ice, was unable to descend into it. In the 

 second cave he had again cut through a curtain of ice into an icy 

 tunnel ; but this year the diameter of the tunnel was so much smaller 

 that he was unable to descend it, although provided with ropes for 

 the purpose. He described some flies found inside the tunnel. The 

 third cave had not previously been explored ; it was an oval in shape, 

 with a level floor of ice. He had descended for about 12 feet 

 between the ice and the rock, and there found a narrow tunnel which 

 appeared to lead to a subglacial reservoir containing water. He 

 ascertained that the ice was at least 24 feet thick ; but it was impos- 

 sible to descend the tunnel. 



Mr. Bonney, who had accompanied Mr. Browne, made some ob- 

 servations on the general character of the country, expressing his 

 opinion that the glacieres were formed by the accumulation of snow 

 in suitable fissures ; and remarking that the prismatic structure of 

 the ice noticed last year by Mr. Browne was very conspicuous. 



