In addition to learning shorthand I am also a radio/morse code hobbyist.
From that realm I found (again) a contemporary to Greg that was used as a “short hand” by commercial telegraphers and wire services for increasing the speed of infromation transmission over the wire.
In 1879 a man named Walter Phillips standardized a set of abbreviation used by telegraphers at the time. The result was the Phillips code. The last version published was in 1925.
Here are a couple links to books. I find them quite interesting and return to them occasionally. Most of it is a list of abbreviations, but both links contain quite a bit of text including a biography of Phillips.
Some of the abbreviations will seem strange. A lot of these are a result of being intended for morse code. Some of those strange things will sound like (i.e. “suggest” the sound of) other characters when the whole is put together. They were working with different “material” as JRG would say.
Anyway, here are some links for those who are interested.
The 1925 version of the book transcribed into HTML
An abridged version
On a related note, it is interesting to see the similarities of approach to teaching morse code and shorthand in the books written in this period. The approaches are different, but they seem to rey on the same underlying assumptions.