A grayscale illustration from a scanned book showing noisy paper background.
<bdi><a href="https://en.wikipedia.org/wiki/en:Franz_Reuleaux" class="extiw" title="w:en:Franz Reuleaux"><span title="German mechanical engineer">Franz Reuleaux</span></a>
</bdi>
1876
<a rel="nofollow" class="external free" href="https://archive.org/stream/kinematicsofmach00reuluoft#page/46/mode/2up">https://archive.org/stream/kinematicsofmach00reuluoft#page/46/mode/2up</a>