The note-book gives the air temperature on the summit as 7 deg. F., taken by a standard alcohol minimum thermometer, and it remained constant during the hour and a half we were there. The sun was shining, but a bitter north wind was blowing. But the reading of the thermometer attached to the barometer is recorded as 20 deg. F. I am unable to account for this discrepancy of 13 deg. The mercurial barometer was swung on its tripod inside the instrument tent we had carried to the summit, a rough zero was established, and it was left for twenty minutes or so to adjust itself to conditions before an exact reading was taken. It was my custom throughout the ascent to read and record the thermometer immediately after the barometer was read, but it is almost certain that on this momentous occasion it was not done. Possibly the thermometer was read immediately the instrument was taken out of its leather case and its wooden case and set up, while it yet retained some of the animal heat of the back that had borne it, and the reading was written in the prepared place. Then when the barometer was finally read, no temperature of the attached thermometer was noted. This is the only possible explanation that occurs, and it is very unsatisfactory. It was not until we were down at the base camp again that I looked at the figures, and discovered their difference, and I could not then recall in detail the precise operations on the summit. It is hard to understand, ordinarily, how any man could have recorded the two readings on the same page of the book without noticing their discrepancy, but perhaps the excitement and difficulty of the situation combined to produce what Sir Martin Conway calls "high altitude stupidity." [Sidenote: In Exculpation]