GENERAL. a. Use. (1) The barometers described
in this manual are
aneroid-type barometers used to measure the pressure of the atmos-
phere. Aneroid, from the Greek a (no) + neros (wet) means "con-
taining no liquid." The greatest advantage of the aneroid is its port-
ability. It is widely used where the use of the mercury barometer would
be inconvenient or impractical. It is also valuable in giving relative
indications and in measuring pressure changes over a few hours.
(2) Apart from the measurement of pressure, there is a broad field
for the use of the aneroid barometer in determining height above sea
level or above the ground, and in determining differences in elevation
between two points. When used to measure height, the aneroid is called
an altimeter. Altimeters are widely used in aircraft and in surveying.
(3) The barometers covered in this book are designed for use in
fixed or mobile stations and for transport by hand or in vehicles.
(4) Each barometer is an integral unit requiring no additional
equipment to accomplish the purpose for which it is intended.
b. Reliability. The aneroid barometer
is less accurate than the mer-
cury barometer. It should not be depended upon for measurement of
absolute values of pressure unless it is compared at intervals of 90 days
or less with a mercurial barometer for which errors are known.
Note. The aneroid barometers covered by this technical manual are much more
accurate than former types of aneroid.
c. Nomenclature. (1) Throughout this manual Barometer ML-102-
(*) refers to Barometers ML-102-B, M L -1 0 2 -D, ML-102 -E, and
ML-102-F, or any one of them.
(2) Any reference to "the barometer" includes Barometer ML102-
(*) or ML-316/TM. If Barometer ML-316/TM only is indicated, the
complete nomenclature is used.
a. Barometers ML-102-B, ML-102-E, ML-102-F.
(1) Pressure measuring and indicating system. (a) Pressure sensitive
cells (five in Barometer ML-102-B; two in Barometers ML-102-E and
(b) Lever system.
(c) Indicating pointer.
(2) Metal case. (a) Metal base.
(c) Plastic window and snap ring.
(3) Mounting frame assembly. (a) Metal frame in two sections.
(c) Temperature correction chart and nomograph supplied for
Barometer ML-102-E only.
(4) Carrying case with strap.