Thank you for posting the link to Hank Johnston's article, Dan!
It is hard to tell how many people took advantage of Anderson's
rope to reach the top of Half Dome between 1875 and 1884. Estimates
are in a wide range between fifty and several hundred climbers.
However, after Anderson's death in 1884
(when his ropes were swept away), and all the way to 1919
(when McAllister's cable route was finally erected) the number of
ascents trickled to just a few.
If you are interested in learning more about those early
Half Dome ascents, I collected several dozen original articles from
old newspapers and books and posted them to the Web. The document
is organized in two parts: Part 1 covers Anderson's years (1875-1884),
and Part 2 talks about the period between 1884 and 1919.
One big puzzle remains unsolved: Was Jack London one of the
few climbers who made it to the top of the Dome in that second period?!
http://highwire.stanford.edu/~galic/stanford/halfdome/Enjoy! -Harv