HUMAN LIMITS IN FLIGHT—MATTHEWS 279 
mountains. In the latter case, weeks are spent at 15,000-18,000 feet to 
become acclimatized to the thin air. Great changes occur throughout 
the climber’s bodily processes which enable him to live at altitudes 
which are fatal to a “sea level” man. Acclimatization is soon lost on 
return to ground level, so it is not possible to make much use of this 
in flying. 
Climbers have reached 28,000 feet on Mount Everest, but in con- 
trast to this the first serious high-altitude accident occurred in 1875 
when Tissandier with two companions went up in the hydrogen bal- 
: U.S. ARMY 
@ ees 
1935 
PICCARD 
57600 
1934 
ONATI 
HS 400 1934 
Xu 
WINS 
44.000 1932 
STRATOSPHERE 
-50°c. -70%F. 102° of frost 
FESS SHROEDER 
{Jeo 36.000 1920 
° TISSANDIER 
ROBERTSON 28.500 1875 
6000 
1804 
GLAISHER 
& COXWELL 
28.000 1862 GARR 
OS 
18.000 1912 
CHARLES 
13.000 
1785 
MONTGOLFIER 
M 
14400 1909 
EARTHS SURFACE 
TEMPERATURE 
Figure 5.—Balloon and aircraft altitude records. (Heights to the nearest 100 feet.) 
loon Zenith. The balloon ascended to about 26,000 feet and the 
occupants became unconscious. ‘They became conscious again when 
the balloon descended to 20,000 feet but then threw out ballast and 
the balloon rapidly ascended to about 28,000 feet. All became un- 
conscious and when Tissandier regained consciousness the balloon was 
at about 19,000 feet, descending rapidly, but his two companions were 
dead. This accident focused a great deal of attention on the 
physiological problems of altitude, and to investigate these Paul Bert 
constructed a steel chamber from which the air could be removed by 
a pump to simulate altitude conditions at ground level. Since then 
a great deal of research has been carried out in such decompression 
619830—45——19 
