24 A CONTRIBUTION TO THE STUDY OF ICE-STRUCTURES 



PLATE VI 



Figure 1. — Looking from a distance of twelve inches into a growth of composite blade- 

 like ice-crystals formed on the wall of the Low-temperature Laboratory. 

 Figure 2. — A distant view of the same. 



PLATE VII 



Figure 1. — Frost-ice formed at —30° F. on the face of the spectroscopic camera. 

 Figure 2. — Hexagonal crystals of clear ice formed by sublimation on a seal liver which 

 had been buried during the winter. 



FIGURES IN THE TEXT 



PAGE 



1. Diagrammatic representation of the section at Priestley's July shaft in 



Green Lake 6 



2. Section of Shallow Lake 9 



3. Priestley's July shaft in Blue Lake 12 



4. Section exposed in Priestley's shaft, Coast Lake 14 



5. Cross-section of stalactite developed from a brine solution. (Actual 



size) 17 



6. Ice-scale with trigonal symmetry ; a unit in plate formation. (Greatly 



enlarged) 19 



