Sir,

A new tunnel at an elevation of 4220 m. was started on Monte Rosa at lat. 87.6° N. and long. 632.4° E. on the Swiss Topographical Map, headed due south-east and graded horizontally into the steep ice slope. The tunnel pierced through to bed rock at 92 m.

This year I had a group from the Austrian Alpine Club who occupied a chamber excavated in the snow continuously for two months except for three days during a September blizzard. The temperature readings are fascinating: starting with 8° F. (− 13.3° C.), which obviously is the mean annual temperature of the atmosphere at this altitude, the ice grew progressively warmer as the tunnel advanced, reaching 17° F. (−8.3° C.) at 30 m.; then the ice dropped to 10° F. (−12.2° C.) at 50 m.; the ice warmed up again to 17° F. at 70 m.—then dropped to 8° F. at 90 m.—and the rock itself was at 8° F.

These temperatures varied very little over the whole exposure of the tunnel opening—up to three months. They are not to be interpreted as applying to the old tunnel.

Temperatures of the air outside and inside the tunnel were also recorded during the summer.