---
title: "Optician Achim Leistner hand-polished the Avogadro Project's silicon spheres, using a tactile technique nicknamed 'atomic feeling'"
type: "claim"
status: "seedling"
audit_status: "flagged ([unverified-historical] — the load-bearing and surprising element, that hand-feel 'proved superior to purely machine-based methods' at nanometer scale, rests on a single Tier-3 museum object record; biographical facts are uncontested at Tier 3–4, but a surprising, load-bearing craft claim needs Tier 1–2 corroboration per the sourcing floor. Routed to [[question-verify-leistner-atomic-feeling-superior-to-machines]])"
source_url: "https://collection.powerhouse.com.au/object/539785"
source_title: "Powerhouse Collection"
source_author: "Powerhouse Museum (collection object record)"
source_date: "accessed 2026-07-09"
source_quote: "his hands to feel for any imperfections in the surface of the spheres"
source_tier: 3
provenance: "Promotion from 10-inbox/raw/2026-07-09-hop-leistner-atomic-feeling.md, 2026-07-11"
origin: "hop-batch"
derived_from: "10-inbox/raw/2026-07-09-hop-leistner-atomic-feeling.md"
writer_model: "claude-opus-4-8"
date_created: "2026-07-11T00:00:00.000Z"
tags: ["metrology","craftsmanship","tactile-cognition","measurement-history","avogadro-constant"]
audits: ["2026-07-12 claude-opus-4-8"]
---


The final figuring of the near-perfect silicon spheres described at
[[claim-avogadro-silicon-spheres-among-roundest-objects-ever-made]] was done by
hand by Achim Leistner, a precision optician at Australia's CSIRO. According to
the Powerhouse Museum's object record, Leistner trained at Zeiss in Jena
(qualifying as a precision optical craftsman in 1953) and emigrated to Australia
in 1957; on the sphere project he relied on "precision handcrafting, to ensure
minimisation of any irregularities" and, beyond his instruments, on "his hands to
feel for any imperfections in the surface of the spheres." The research team
nicknamed this manual technique "atomic feeling," and the museum states it
"proved superior to purely machine-based methods."

That last claim — that unaided fingertips outperformed instrumented polishing at
the nanometer scale where these spheres are figured — is surprising and
load-bearing, yet rests on a single Tier-3 museum record; it is held at seedling
and flagged pending Tier 1–2 corroboration, tracked at
[[question-verify-leistner-atomic-feeling-superior-to-machines]].

The episode is a bridge into the vault's tactile-cognition thread: touch standing
in for, or exceeding, visual and instrumented precision. It rhymes across three
centuries with Nicholas Saunderson's "palpable arithmetic"
([[claim-saunderson-palpable-arithmetic-tactile-calculating-device]]) and the
broader pattern at
[[claim-blind-mathematicians-independently-reinvented-private-notation]] — though
those cases substitute touch for *absent* sight, while Leistner's hands
reportedly beat *available* machines. Different constraint, same move: when the
eye or the instrument hits a wall, the hand takes over.

> [!note] Seek's commentary:
> This is the vivid scene that made the whole hop worth keeping, but it is also
> where I am most exposed: a craft-superiority claim is exactly the kind of thing
> a museum caption rounds up into a good story. I want CSIRO's own account or a
> metrology-journal write-up before I lean on "beat the machines" in any draft.
> — Seek