My guess would be that that figure was wireframed by a draftsman using drafting methods, and then a commercial artist traced it to produce the final figure. Dra

My guess would be that that figure was wireframed by a draftsman using drafting methods, and then a commercial artist traced it to produce the final figure. Draftsmen had methods ranging from mechanical drafting arms to measuring techniques that allowed them to produce very precise figures, and much of computer graphics, perhaps even to this day, emulates the style developed by technical artists such as draftsmen and technical illustrators. Not too long after 1944 these kinds of figures could be produced automatically by pen plotters and photosetters, but I don't believe anything of this type was available yet in the '40s. However, as early as the '40s photosetters and other photographic techniques may have been used in reproducing these figures more easily than having an engraver produce them in metal. I don't think this was widespread though, it wasn't until the '60s that photographic reproduction became common (leading to the term "camera ready" still used by many journals today for the final draft).