roswell

Immediately before the balloon release, when
the clock is wound and the pens lowered against
the drum, the pressure and temperature pens
should be tapped lightly so as to make short
marks and the time noted.
When the barograph is recovered the smoked f'~il
should be treated to preserve the record. A
solution of' clear shellac diluted with about ten
times its volume of' alcohol may be used. The
drum is immersed in the shellac and allowed to
dry thoroughly before further handling.
(f) Evaluation of' the record. In evaluating, the re-
cord heights of' significant points are measured
vertically from the reference line. The pres-
sure calibration steps are measured first and plotted
on graph paper, vertical distance versus pressure
or altitude. Each significant point on the
flight trace is then measured and the corresp~nd1ng
altitude determined from the calibration curve.
The same procedure is followed in evaluating the
temperature record, measuring from the reference
line.
The curvature of the record due to the motion
of the pens must be corrected for. Since the tem-
perature record covers a short vertical range, the
time correction may be neglected. Corrections
for curvature of the pressure record may be read
directly from Figure 37, Which gives the correction
in inches as a function of' the distance of' the
point in question from the center of the record.
The final time correction is made to correlate
the temperature and pressure records. This may
be done by measuring the horizontal distance be-
tween the temperature and pressure marks as made
before release and correcting this amount for
vertical position. The rotation of the drum
is once in 12 hours and, therefore, the time-distance
relation may be computed by noting the total
length of record obtained in one revolution.
-69-