Thirst and loss of appetite were the first symptoms experienced by Dr Barry at a height of about 14,000 feet; but it was not till he reached a height 1000 feet greater, that exhaustion and fatigue supervened. A tendency to fainting was felt, and a total indifference to the main object of the journey. After a few minutes of rest, these sensations disappeared, but were again perceived on proceeding a few steps. On the summit (15,666 feet above the sea; Barom. 17.052, Detached Therm. 30°) no particular lassitude was felt while the author performed his experiments. After the descent the author did not suffer from a state of collapse.