In another question, I was asking about the origin of the reduced Planck's constant, $\hbar \equiv \frac{h}{2 \pi} .$ Specifically, I wanted to know why the symbol $`` \hbar "$ was selected for the value $\frac{h}{2 \pi} ,$ where $h$ is Planck's constant.
I found a presentation that claimed it was introduced in a 1926 article:
–Page 17 of "The Planck constant h and the Dirac constant ħ. Their units and their history", by Ian Mills and P. R. Bunker. [PDF]
This seems to make it clear that that article used the symbol, $`` \hbar " .$
However, in checking the cited journal article, it seems to use the symbol $`` h "$ instead.
–Page 1 (printed-page 661) of "On the theory of quantum mechanics", Paul Dirac (1926-10-01). doi:10.1098/rspa.1926.0133.
This would seem to suggest that the presentation claiming that $`` \hbar "$ appeared in the 1926 article was mistaken, if the above screenshot is representative of the 1926 article.
However, as noted in one answer to my question, this article was printed around the time it became possible to use $`` \hbar " .$ So, it seems possible that some printers may've actually used $`` \hbar " ,$ as claimed in the presentation, while the screenshot above shows a different printing that fell back on $`` h " .$
Were such printing variations something that tended to happen in the past? Or, were printings kept more uniform, e.g. done by a single shop in a single go?
Questions:
Historically, have printings of the same journal article contained minor typographical variations?
Is there an easy way to check if printings of a particular article had a particular variation between printings? For example, is there an easy way to check if the 1926 article discussed above used $`` h "$ in some printings vs. $`` \hbar "$ in other printings?