200 
ments were not, however, designed 
particularly for this problem. 
Future experiments in this field will 
aim at still lower wave lengths and 
greater resolution. 
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ANNUAL REPORT SMITHSONIAN INSTITUTION, 1948 
Although we have a vehicle which 
will carry us to an undreamed-of 
altitude, the problem of measuring 
such basic quantities as pressure and 
temperature from a missile which is 
Be | ap 
ALTITUDE — KM ABOVE SEA LEVEL 
FicurE 7.—Variation of pressure with altitude. 
Pressure and Temperature Experiments 
Actual measurements of pressure and 
temperature in the upper atmosphere 
have been made for many years by 
various methods. Balloons regularly 
obtain this information up to 30 km. 
Above this altitude various indirect 
methods have been used, including 
measurements on meteors (29), sound- 
range measurements of large explo- 
sions (30), and others (2). 
moving at a velocity of 1 mile a second 
is far from easy. This becomes clear 
when one calculates the adiabatic 
temperature rise on a thin piece of 
material placed on the nose of the 
V-2. For the velocities involved this 
temperature is higher than 1000° C. 
Our attack on the problem to date 
has been to measure the so-called ram 
pressure at the nose of the missile and 
the pressure at a point on the side of 
the missile at which, according to 
