Only one form of natural ice has been proved to exist at ordinary pressures. The positions of the oxygen atoms are known definitely from X-ray investigation. These form an open-work structure in which each oxygen is surrounded tetrahedrally by four others, the whole system having hexagonal symmetry. The positions of the hydrogen atoms between each pair of oxygens are not known with certainty, perhaps because they may be continually changing. Curious diffuse X-ray patterns, which are related to the temperature of ice, have yet to be explained in detail, but may throw light on the atomic movements. A cubic form of ice may exist at temperatures below −70° C. and under special conditions, and some less symmetrical high pressure forms have also been studied.

In the middle of last century, Agassiz, Tyndall and others showed that a glacier flowed faster at its centre than at its margin. Partly from experiments and partly from the assumption that it behaved like a river, it became generally accepted that it also flowed faster at the surface than lower down. This belief was held until ten or fifteen years ago although search through earlier literature shows that evidence was accumulating which might disprove this.

The evolution of snow and glacier research in Switzerland is outlined. The settling, creep, viscosity and slipping of the snow cover are discussed in detail and the relationship of these comparatively simple processes to the more complex movements in a glacier are described. The importance of further research in glacier physics in connection with the crystallographic and mechanical properties of ice is stressed; certain preliminary laboratory experiments and some subjects for further research in the field are suggested. The Great Aletsch Glacier is recommended for this owing to the proximity of the Jungfraujoch Research Institute and facilities for transport by the Jungfraujoch Railway.