roswell

t.mperature recording is confined to the lo'tier
2 inches of the drum so as to interfere as little as
poasible with the pressure record when the bel loon
float• above 30,000 teet.
Recording is accomplished by three pens which scratch
carbon from a smoked aluminum toil. This method
eliminates the need :for liquid ink and applies a
minimwn of pressure to the recording drum.
The recording dr~ rotates once in twelve hours.
Therefore, it a :flight lasts over twelve hours, the
trace will overlap. Such a record is shown in
Figure 36. The clock runs for 36 to 40 hours on
one winding.
Preparation of the barograph :for use on a balloon
a~ension requires the followinga
(a) Place an aluminum :foil about 10 inches long by
3 3/4", .002" thick on the drum. Care should
be taken to have the overlapping edge of the
:foil :face in the direction of rotation of the
drum so the. t the stylus &lides ott the edge in-
stead ot catching and tearing the :foil. A few
drops of rubber cement along each edge or the
:foil are sufficient to :fasten the roil to the drum
and will not interfere with removal of the foil
after reoovery or the barograph.
(b) Wind the clock. The clock should not be wound
tightly since at the low temperatures encountered
in the upper atmosphere the clock spring may
snap. However, if the clock is wound an hour
or so before release, it·will be sufficiently
relaxed by the time the low temperatures are
reached.
(c) Check pressure of the marking pens. Too much
pressure of the pens on the drum will introduce
an error due to the frictional lag. When the
drum is removed :from the clock mechanism, and the
pen lifter released, the stylus points should
touch the clock housing lightly.
(d) Smoke the drum. A very thin, tine-grained carbon
film should be deposited on the aluminum foil.
The best result will be obtained by use of a
bright yellow gas flame, although a kerosene flame
gives a satisfactory coating. Solid or liquid
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