A Brunsviga 15 mechanical calculator with serial number 202550. The shrouds had been removed to reveal the internal mechanic. Produced by Brunsviga-Maschinenwerke Grimme, Natalis &amp; Co. AG, Braunschweig between 1934 and 1947.
<a href="//commons.wikimedia.org/wiki/User:Cccefalon" title="User:Cccefalon">CEphoto, Uwe Aranas</a>
CC BY-SA 3.0
<span class="int-own-work" lang="en">Own work</span>