Why do we keep wet cloth on forehead of person having fever?
Heat is more rapidly dissipated through the head. Placing a wet cloth on the forehead creates evaporation, a cooling effect. It's an age old remedy that doesn't work very well, a cool bath is much better.
The reason why we keep wet cloth on the forehead of a person having fever is to reduce the fever. By so doing, it will feel a bit cool and also pleasant to the person with fever.