Engineering drawing of a binocular spy-glass
<a href="//commons.wikimedia.org/wiki/Moritz_Hensoldt" title="Moritz Hensoldt">Moritz Hensoldt</a>
circa 1900 <div style="display: none;">date QS:P,+1900-00-00T00:00:00Z/9,P1480,Q5727902</div>
Scan by Christine Belz-Hensoldt