Gossen Parvux light meter.
The Parvux is a light meter intended to measure the ambient light in Lux
at a given location. The basic meter is equal to most of the Gossen
meters from this time. The first meter was the Photolux and the
difference is the scale. Where all the photometers have a lens in front
of the Photocell has the Parvux jest a glass window. The measured value
is in Lux.
The aluminum plate gives some information about lighting for area's like
workshops and living rooms.