Vintage wind up Mercedes Clock 

art nouveau style 

The silver coloured part is thin metal.  There looks like there may have been a hallmark in the bottom left hand corner.
I have tried to take a close up photo of it, but it is very faint, so cannot confirm that it is silver.

Made In Germany 

Size (approx.): 10.3cm tall, 9.5cm wide

Condition: Metal surround is dull and tarnished - needs a good clean and polish.
Dark coloured case is worn at the edges. 
 Fully wound but starts briefly then stops. None of knobs turn to move the hands.

Therefore selling as non-working for restoration or spares