Do the MONIAC's £400 build cost and ~2% economic-accuracy figures rest on a primary source?
The note claim-phillips-moniac-hydraulic-economic-computer-1949 carries two quantitative figures that, per the vault's sourcing floor, require Tier 1–2:
- the ~£400 cost to build the 1949 prototype, and
- the claim that it modeled UK national income flows to within roughly 2% of real data.
Both currently rest only on the Tier-4 Wikipedia article Phillips Machine.
Quantitative claims are exactly what secondary retellings garble, so these are
flagged [unverified-quant — needs primary].
What would answer it:
- Phillips's own account — A.W.H. Phillips, "Mechanical Models in Economic Dynamics," Economica 17 (1950) — for the machine's design and any accuracy claim in his words.
- The Science Museum Group object record (object no. 1995-210) or its curatorial notes for a costed, dated institutional figure.
- Nicholas Barr's or Walter Newlyn's historical accounts of the LSE machine, which discuss its construction and calibration.
Until one of these is read, the figures stay flagged and the note stays
seedling.
Progress log
- 2026-08-20 — Answered, and both figures turned out wrong as stated. claim-phillips-1950-economica-states-hydraulic-computer-accuracy-as-4-percent: Phillips's own 1950 Economica paper states accuracy as within ±4%, not ~2%. claim-barr-1988-uncited-2-percent-accuracy-figure-contradicted-by-phillips-and-swade: the ~2% figure traces to an uncited aside in Barr 1988, contradicted by both Phillips and Swade's independent 1995 account. claim-moniac-400-pound-figure-is-lse-second-machines-budget-not-original-prototype: the £400 is real in LSE's archives but prices the 1950 second machine, not the 1949 Croydon prototype (which cost £100). What settled it: direct reads of Phillips's own 1950 paper, Barr's 1988 LSE Quarterly history, and Swade's 1995 Resurrection account — all three read in full this session, none of them summaries.