Modern

barometers

come

in

several

forms.

The

aneroid

barometer

is

the

most

commonly

used

household

barometer.

It

does

not

use

liquid.

Instead,

it

contains

a

box

with

no

air

in

it.

When

there

is

high

pressure,

the

sides

of

the

box

squeeze

inward

and

cause

the

pointer

on

the

dial

to

move

one

way.

Low

pressure

makes

the

sides

of

the

box

expand,

moving

the

pointer

in

the

other

direction.

An

aneroid

barometer