Is blind mathematicians' independent reinvention of private notation a real recurring pattern, and why is there no visible transmission between cases?

The observation note claim-blind-mathematicians-independently-reinvented-private-notation proposes that blind mathematicians repeatedly devised their own bespoke systems to work without sight — Saunderson's tactile board, Pontryagin's mother-invented oral glosses, Euler's memory/dictation — each apparently improvised independently, with no shared apparatus and no line of descent between them. On current evidence this is two well-attested cases plus one lead, resting entirely on Tier-4 Wikipedia. Two distinct things need settling before it graduates from hunch to thread.

Why it matters. If real, it reframes assistive mathematical notation as a recurring, independently-reinvented improvisation rather than a modern category — and the absence of transmission (later blind mathematicians not inheriting earlier workarounds) would itself be the interesting finding, a small case study in how tacit adaptations fail to propagate.

What would answer it:

1. Corroboration / a third case, ideally contemporary. Find at least one more documented instance — a modern blind mathematician (e.g. Bernard Morin, or present-day cases) and their working method — to test whether the pattern holds beyond two anecdotes, or whether modern braille-mathematics / screen-reader standards broke the "each reinvents from scratch" shape.
2. Primary sources to lift the notes off seedling. Read MacTutor and a DSB/ODNB biography on Saunderson for the actual mechanics of the palpable-arithmetic pin-board; read a scholarly Pontryagin biography or Boltyanskii's reminiscences to confirm the "tails up" anecdote and the mother's role; source Euler's post-blindness working method and the "~50% of output" figure (a quantitative claim needing Tier 1–2).
3. The transmission question directly. Did any of these figures know of an earlier blind mathematician's method? Is there any evidence of inheritance, or is the independence genuine?

Candidate next moves. Chase the Euler lead the capture saved; check whether Saunderson's manuscripts really influenced John Harrison (a separate saved hook in the capture, still unverified); look for a history-of-disability-in-mathematics survey that may have already made or refuted this argument.