_1. Sinking experiments without oxygen breathing_
Since a thoroughly dependable parachute oxygen apparatus is not yet
generally available, experimental tests were made to determine from what
altitudes a rescue with open parachute without oxygen is possible.
Therefore, sinking experiments were carried out in which the mask was
taken off after ascent with O_{2} (for speed of ascent of the chamber
see fig. 1), and, after a waiting period of 10 seconds the sinking was
begun.
In the experiment no altitude sickness occurred at 9 km. [29,500 ft.] as
was expected.
In the sinking experiments, from 10 km. [32,800 ft.] altitude, typical
altitude sickness occurred after about 2 minutes, i. e., at an altitude
of about 8.6 km. [28,200 ft.], which was indicated by a very pronounced
scrawling in the writing test. However, no loss of consciousness
occurred. (Kloos’ writing test.)
[page 7 of original]
The experiments from 12 to 15 km. altitude were made partly during
suspension in a parachute harness, partly in a sitting position, and
partly in a prone position. These experiments show that the body
attitude has a very essential influence on the tolerance for a high
degree of lack of oxygen. Since, besides this, every bodily exertion is
of great importance, in one portion of the experiments six knee bends
were made by the subject during the waiting period before beginning the
descent. These six knee bends consisted of three knee bends while
breathing oxygen followed by deep inhaling and holding of the breath,
and then three more knee bends without oxygen breathing. This procedure
was chosen in order not to neglect the bodily work involved in an actual
parachute jump. The descending experiments from 12 km. [39,400 ft.]
altitude yielded the following average times: