Vintage Pocket Watch Dead Beat Voltmeter Measuring 0-10 Volts and 0-100 Volts

This is a  1930/40s Vintage Pocket Watch Dead Beat Voltmeter Measuring 0-10 Volts and 0-100 Volts. I can't find a maker's mark.

In fair condition, there is some discolouration, loss of chrome, and surface scuffing commensurate with age and use.  It has not been tested and I don't know whether or not it is working. It is being sold as a collectible, for display only.

The face is labelled with words written in French, English and German as follows:-

Volts

Aperiodique

Dead Beat 

Knopf gedr. 10V (Press black button for the 10V scale)

The top scale measures 0-10 volts, and the bottom scale measures 0-100 volts. 

Approximate Size: 5.5cm in diameter & 2.5 cm in depth.

This piece of vintage technology would have been carried around in a pocket as a handy tool for the engineer to make a quick (but not necessarily accurate) measurement. It now makes an interesting display item for a vintage engineering tool collector, or a tactile desk ornament. 

Please click on the following link for more vintage test meters.
SaveSave