Details of the original <a href="//commons.wikimedia.org/w/index.php?title=SOHC&amp;action=edit&amp;redlink=1" class="new" title="SOHC (page does not exist)">SOHC</a> valvetrain for the earliest examples of the German Mercedes D.III aviation engine - note the rocker arm emerging from the "rocker box" through a slot in the box's side, later replaced with front-side rocker arm rotary driveshafts to eliminate the slotted arm aperture.
Unknown, artist's name is indistinct where it was signed in the scan.
1915-12-03
British-origin Flight Magazine, December 3, 1915 issue, page 948.