d. U s e a d r y c l o t h f o r c l e a n i n g . A w a t e r
protect it from the. Snowtight lockers
which stay at outdoor temperatures are
are damped cloth will either freeze to the
mirror or it will leave a film of ice and
recommended as a place for keeping the
make it inoperable.
compass. If it is necessary to bring in-
e. D o n o t p e r m i t t h e a c c u m u l a t i o n o f
struments from low temperatures to
room temperatures, "anticondensation"
snow or ice on the compass. When not in
use, always keep the compass inside car-
containers should be used. These con-
tainers can be specially made boxes or
rying case M19 to prevent such accumu-
any other fairly airtight containers with
lation.
heat-conducting walls. Keep them outside
f. Never
apply
heat
from
strongly
con-
centrated sources directly to an extremely
80 they will remain at prevailing tem-
peratures until it is desired to bring the
cold compass. Sudden changes in tempera-
instrument indoors; then put the instru-
ture may cause breakage of the component
ment into the container, close the top,
parts of the compass.
bring it indoors and let it come to room
temperature. When the instrument is at
room temperature, the container can be
Sandy
Conditions
opened and the instrument removed with-
Under
extremely
dusty
or
sandy
condi-
out condensation forming on it. If anti-
tions, extra care must be exercised when
condensation chambers are not used and
cleaning the compass so that scratching
instruments are brought into a heated
or marring of the mirror does not occur.
room, condensation will occur and the in-
Shake all dust and sand from the carrying
strument will have to be wiped thorughly
case.
dry. Use only lens tissue paper for drying
glass.
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