It should be kept in mind in regard to the experiments conducted in the sitting position that the subjects fell over at the beginning of unconsciousness and so passed the critical time of greatest load on the circulatory system in a prone position, while those suspended in the parachute harness remained throughout the experiment in a vertical position, the most unfavorable position for loading the circulatory system. [Illustration: Figure 1. Speed of ascent in the portable low-pressure chamber.] In the writing test shown above [not reproduced] the occurrence of altitude sickness in a sinking experiment for 12 km. [39,400 ft.] altitude is shown in this manner: For example, after 1 minute and 20 seconds at 11 km. [36,100 ft.] altitude, the writing is interrupted because of sudden altitude sickness with unconsciousness, and is resumed after 4½ minutes at an altitude of 8.8 km. [28,870 ft.], with erroneous writing. At 8.3 km. [27,230 ft.] altitude the writing becomes free of errors. This is worthy of special attention because in this case a person has fully recovered mentally at an altitude of 8.3 km. [27,230 ft.], after 3 minutes of the most severe lack of oxygen, while in altitude endurance experiments at this altitude severe altitude sickness sets in after about 3 minutes. Here we are dealing with a process which in any case is very favorable but which is not yet entirely clear and which was already observed in earlier experiments of parachute jumps from great altitudes. Still, it appears from this that a rather long oxygen lack at altitudes up to 13 km. does not present any great strain in [page 12 of original] the sense of using the last reserves, but, on the contrary, the human organism seems to react to this loading with a certain increase in resistance to altitude. In descending experiments from 13 km. [42,700 ft.] altitude the waiting time of 10 seconds was retained, but on the other hand exertion in the form of knee bends was omitted since technical difficulties interfered with this procedure. The experiments involving suspension could be done only in the large low-pressure chamber, since suspension was impossible in the small low-pressure chamber for reasons of space. Therefore, the ascent to 13 km. [42,700 ft.] altitude was carried out slowly in the main chamber (without explosive decompression) so that when 13 km. [42,700 ft.] was reached a certain oxygen lack existed. With this oxygen lack the knee bends would have presented a great burden which would have falsified too greatly the results of the experiment. The same conditions were also given in further experiments at higher altitudes in the main chamber. For this reason, the 13 km. [42,700 ft.] descending experiments were carried out partly in the sitting position, partly in the sitting position strapped in, and partly suspended. They yielded the following average data: Table 2