Question mark
The rhetorical question mark or percontation point was invented by Henry Denham in the 1580s and was used at the end of a rhetorical question; however, its use died out in the 17th century. It was later revived in modern-day society by Matt DiRoberto. It was the reverse of an ordinary question mark, so that instead of the main opening pointing back into the sentence, it opened away from it. This character can be represented using the reversed question mark (⸮) found in Unicode as U+2E2E. The percontation point is analogous to the irony mark, but those are even more rarely seen.
Question Mark (aircraft)
The flight of the "Question Mark" did spark an interest in aerial refueling by the Royal Air Force, seeking to minimize takeoff weights of its bombers and reduce wear-and-tear on its grass airfields, but after a series of experiments between 1930 and 1937 they abandoned testing. The development of better engines, variable-pitch propellers and all-metal low-wing monoplanes capable of greater range deferred further military interest in aerial refueling, but when the next war turned out to be global in scale, also resulted in lack of capability for many ferrying, antisubmarine, and bombardment operations requiring extended range.