What is Barograph?

A barograph is a recording aneroid barometer where the changes in atmospheric pressure are recorded on a paper chart.

Principle & Working:
The principle of the barograph is same as that of the aneroid baromoter. A metal box partially exhausted of air (vaccum) will undergo changes of shape as the outside pressure varies. These small movements of the box are transmitted by a system of levers to a  recording arm that has at its extreme end either a scribe or a pen. A scribe records on smoked foil while a pen records on paper using ink, held in a nib. The recording material is mounted on a cylindrical drum which is rotated slowly by a clock. Commonly, the drum makes one revolution per day, per week, or per month and the rotation rate can often be selected by the user.

barograph types

List of types of barograph used by countries under Voluntary Observing Ship Scheme (VOS Scheme)