that others are liable to bleeding at the nose, or habitually suffer from headache, and that this accounts for much which has been laid to rarefaction of the air; and further, it is said, or conjectured, that the fatigues inseparable from travel in mountain-regions account for more: in short, that mountain-sickness is to be attributed to the frailties of human nature, or to the imperfections of individual constitutions, and is considered as a sign, or indication, of weakness or incompetency.
It is undeniable that there is some truth in these observations, and it can scarcely be doubted that effects which have been produced by fatigue have often, wrongly, been attributed to rarefaction of the air, and that effects which have been produced by rarefaction of the air have often been assigned to fatigue. The immunity from unpleasant symptoms which has sometimes been enjoyed by aeronauts, even when bounding in a few minutes to enormous elevations,[1] has tended to foster scepticism; and has appeared to support the opinion that fatigue and personal imperfections have had much to do with mountain-sickness, and not to accord with the view that it is produced by diminished pressure—otherwise, why should these persons, transported without effort to superior elevations in the air, have escaped, whilst others, at much inferior ones upon the earth, suffer?
It is scarcely necessary to occupy these pages with a mass of
- ↑
The following data are taken from the Reports of Mr. J. Glaisher, F.R.S., to
the British Association for the Advancement of Science, 1862-3—
Date. Time. Barometer. Diff. of Time. Diff. of Pressure. July 17, 1862 9.43 a.m. 29.193 
44 min. 14.55 inches. ” ” 10.27 ” 14.637 
Sept. 5, ” 1.3 p.m. 29.17 33 ” 14.62 ” ” ” 1.27 ” 14.55
April 18, ” 1.17 p.m. 29.66 32 ” 14.85 ” ” ” 1.49 ” 14.81
Starting from the level of the sea, the height attained in each case was about 19,000 feet, without injurious effects being felt. I am not aware that any one, upon the earth, has ever experienced a natural difference of pressure of fourteen and a half inches in less than four or five days.
