This is one of the very few surviving barographs of this unique design. Manufactured by CB Goerz of Berlin circa 1920, its principal advantage is that it records on a continuously rotating chart with a set of magnets behind. The diaphragm stack is linked to a fine chain which is held by the magnets and are then moves on the chart in sequence with the barometric pressure. There is also a barometer dial, in millimetres linked to the same movement. After seven days the chain will reach the bottom of the the chart and start recording again from the top.  A much more detailed description of the instrument can be found in Philip Collins book on Barographs. The one illustrated in his book (see pics) is now owned by a respected colleague. 
I acquired this particular instrument about 25 years and it came with what can only be described as a 'commercial' wooden case (as shown in the picture). I would imagine this would have made and installed in a public or scientific office. I commissioned  the polished oak case (at £1200) to match as close as possible to the diaplay model.
 Ideal for a specialist collector with the ability and time to fine tune the instrument and set it working again.