Record barometric pressure with this mechanical German-made Classic Barograph that measures variation in air pressure and transfers the data through a system of mechanical levers to the writing arm. Housed in a rich mahogany case with glass sides and a polished brass handle, this barograph is equipped with a battery operated quartz movement with 4 diaphragms that rotates the solid brass drum once a week, requires no winding, and is more accurate than key wound movements. The barograph readings are marked on paper charts with a felt tip pen. Both inch and millibar charts are available Mahogany case with glass sides & polished brass handle Quartz movement with 4 diaphragms Requires no winding Chart duration: 7 days Included are: One-year supply of weekly inch charts (121), AA battery, one black felt tip pen (451) (lasts 6-9 months) Millibar charts (120CH) available separately