"There was still, however, another difficulty, which occasioned
me some little disquietude. It has been observed, that, in
balloon ascensions to any considerable height, besides the pain
attending respiration, great uneasiness is experienced about the
head and body, often accompanied with bleeding at the nose, and
other symptoms of an alarming kind, and growing more and more
inconvenient in proportion to the altitude attained.(*3) This was
a reflection of a nature somewhat startling. Was it not probable
that these symptoms would increase indefinitely, or at least
until terminated by death itself? I finally thought not. Their
origin was to be looked for in the progressive removal of the
customary atmospheric pressure upon the surface of the body, and
consequent distention of the superficial blood-vessels—not in any
positive disorganization of the animal system, as in the case of
difficulty in breathing, where the atmospheric density is
