Who designed the Eversharp pencil?

Up until recently, the answer would have seemed straightforward: Charles R. Keeran invented the Eversharp; the design must have been his. But as Jonathan Veley has pointed out, the appearance of the pencil shown in Keeran's first pencil patent is very different from our idea of an Eversharp. Instead of a metal tip, there is a wooden core, while at the other end there is an exposed eraser. Optional eraser covers are mentioned, but the designs shown in no way resemble the classic Eversharp's distinctive crown. All in all, this proto-Eversharp is most un-Eversharp in appearance. Note that no actual example of such a pencil is known, and the patent application for it was filed October 13, 1913.

The advertisement above was published in The Insurance Press of December 1912 (p. 83). By Keeran's own account, this was shortly before he first began thinking about an improved mechanical pencil. It would have been several months before his pencil patent application, and a full year before the first Eversharps were produced -- by Heath, by all evidence.

As the ad and the examples above show, Heath's clutch pencils have the Eversharp look, with the same proportions and the same distinctive crown. I had always thought that these pencils postdated Heath's involvement with Keeran. My reasoning was based upon the assumption that the Eversharp design was Keeran's, and that after Keeran and Heath parted ways, Heath must have borrowed the design for Heath's own pencils -- albeit only for pencils with a clutch mechanism, which clamped the lead, and did not mechanically push it out. Perhaps some components were left over from Heath's manufacturing work for Keeran, and perhaps some hadn't been paid for, allowing Heath to use them with a clear conscience -- or so I speculated.

The Insurance Press ad turns this all upside-down. Keeran invented the Eversharp's internals, but its "skin" was borrowed from a preexisting Heath product. We may never know exactly how Keeran's mechanism ended up being put into the Heath clutch pencil's body.  It might have been Keeran's idea; it might have been suggested by Heath while discussing how best to put Keeran's pencil into production. In any case, the resulting hybrid ended up eclipsing its progenitor. Heath likely didn't mind much, so long as it was producing both. Once Keeran switched production to Wahl it might have been a different story, but by then it was probably too late for Heath to do anything. I have not been able to find any patent for the Heath clutch pencil, either design or utility, even though one example, shown below, is marked "PAT. APP. FOR" on the barrel. This may explain why Wahl was in turn unable to prevent competitors from offering pencils that copied the Eversharp's appearance -- their number is striking, as is the closeness of resemblance.

ADDENDUM: More on the last pencil in the group of four shown in the picture above here.