Unconsciousness │ From— │ Recovery of consciousness after— │ │ after— │ │ 21 sec. = 19.5 km. │20 km. │87 sec. = 10.55 km. [63,980 ft.] │ [65,600 ft.] │ [34,620 ft.] 15 sec. = 20.875 km. │21 km. │60 sec. = 12.9 km. [68,490 ft.] │ [68,900 ft.] │ [42,320 ft.] The astonishing value of 60 seconds = 12.9 km. [42,320 ft.] for the recovery of consciousness in the 21 km. [68,900 ft.] experiment is explained on the basis that this value was obtained from a single experiment with one subject, who had shown himself in numerous other experiments to be especially resistant to altitude. On the other hand the 20 km. [65,600 ft.] values are the average of a series of experiments. IV. Discussion of the Results The descending experiments without oxygen show that the limit for a safe escape with an open parachute lies approximately at a jumping altitude of 13 km. [42,700 ft.], since in a jump from 13 km. [42,700 ft.] recovery of consciousness occurred only at an altitude of 1.6 km. [5,250 ft.], and so one must already consider the possibilities of landing in an unconscious condition with all the attendant dangers. This still does not take into account the heavy demands made on the body by the cold and the consequent risk. The great effect of the body position during the experiment makes it obvious how severe is the effect of every additional demand. While, for example, in the 13 km. [42,700 ft.], experiment upon a seated subject, recovery of consciousness took place after 8 minutes 12 seconds at an altitude of 7.2 km. [23,620 ft.], the suspended subjects recovered consciousness only after 19 minutes at 1.6 km. [5,250 ft.] altitude. Correspondingly also, unconsciousness occurred in the suspended subjects much more rapidly than in those who were seated. The same observation was made in the 15 km. [49,200 ft.] experiments, and indeed those who went through the experiment lying down could already state name and birth date immediately upon reaching ground level although they were paralyzed, while those who had been suspended did not respond at all to speech within this time. Except for one mentally very sluggish subject, the return of normal condition occurred much earlier to those who were lying down, namely within 15 minutes. The descending experiments extended to 18 km. [59,100 ft.] altitude with oxygen breathing showed that, except for the danger of cold, escape with an open parachute is possible from these altitudes even though, practically, no need exists for it.