It is a device that records the changes in relative humidity of the air on a particular screen. The device is composed of a hair warp that is shortened or longer with moisture changes. A lever is attached to this warp. This lever leads to a stability pencil. There are other ways the device starts a cylinder that slows down after tuning. This cylinder makes a full round every day. On the rotating cylinder, a checkered paper plate is installed that can be replaced.

The stability pencil is placed on the screen and by moving the cylinder draws lines in a curve after a day and night can be referred to the device and the humidity fluctuations of the environment from the curves drawn in the last day and night can be obtained.