xl List of Plates 



PLATE To face page 

 X. Views of the entrance of the Morteratsch Grotto, both taken 

 from the same position and showing the slope of Munt 

 Pers behind 288 



Fig. 5. Photographed i/th September, 1907. 



Fig. 6. Photographed 5th September, 1911. The 

 wastage of the ice, due to superficial melting, is shown 

 by the increased exposure of the slope of Munt Pers. 

 The lateral wastage is indicated by the perspective of the 

 figures, and by measurement it amounted to 35-6 metres 

 in the four years. 



XI. The Morteratsch Grotto in Winter 298 



Fig. 7. Taken on i6th January, 1907. Shows the 

 great abundance of hoar-frost on the roof and its 

 absence on the walls. 



XII. The delineation of the grain of the glacier .... 299 

 Fig. 8. Shows the delineation of the grain in winter, 



by the condensation of moisture in the form of hoar-frost 



on the roof of the grotto. 



Fig. 9. Shows the revelation of the grain in summer 



on a pillar in the interior of the grotto, which received 



subdued daylight from the entrance. 



XIII. Discontinuities which cause the appearance of white ice in 



the walls of the grotto in winter 302 



Fig. 10. Shows a very remarkable picture of these 



discontinuities in the north wall, about two metres from 



the entrance. 



Fig. ii. Overlaps Fig. 10 a little and shows the 



comparative absence of white ice one or two metres 



further in. 



XIV. Fig. 12. The Mergelin See 3O - 



The waters are retained by the ice of the Aletsch 

 Glacier, from which small icebergs are frequently 

 detached. 



Fig. 13. On the Morteratsch Glacier. 



