Mention two demerits of a simple barometer and state how they are removed in a Fortin barometer.

The demerits of a simple barometer are —

1. There is no protection for the glass tube.
2. A scale cannot be fixed with the tube to measure the atmospheric pressure.

Fortin barometer removes these demerits in the following ways:

1. The glass tube is protected by enclosing it in a brass case.
2. For accurate measurement, a main scale alongwith a vernier scale are provided.