Antique Barographs, like antique barometers are scientific instruments. The purpose of both is to register the changes in atmospheric pressure. Antique Barographs record these changes on a paper chart, which is wrapped around a clockwork drum that rotates for one week. The charts are changed each week, and can be kept to compare weather from one year to the next.
Read more about Barometers and Barographs Weather Forecasting and Recording here.