Bill Phillips built the MONIAC, a hydraulic computer that modeled the UK economy with flowing water, in 1949
The MONIAC (Monetary National Income Analogue Computer) was a hydraulic analog computer built by the New Zealand economist A.W.H. "Bill" Phillips in 1949. Coloured water flowed through a system of transparent tanks, pipes, valves, and float-driven pumps, standing in for money moving through the national economy: tanks represented stocks such as savings and the money supply, flows represented taxation, spending, saving, and imports/exports, and the levels settled to model UK national income dynamics. The Science Museum Group holds an original as object no. 1995-210 and describes it as an early analog device for economic modeling — an institutional (Tier 1–2) anchor for the object's existence, date, and nature.
Reportedly Phillips built the first prototype in a rented Croydon garage, scrounging war-surplus parts including pieces of scrapped Lancaster bombers. Correction (2026-08-20, see below): the prototype's documented cost was £100 (a Leeds University advance), not the ~£400 long attached to it, and Phillips's own primary account states the hydraulic mechanism's accuracy as within about ±4%, not the ~2% previously carried here. Around a dozen units were later built and shipped to universities and central banks.
The MONIAC is one half of a convergent-invention pair with the earlier Soviet Water Integrator — see claim-hydraulic-analog-computers-independently-invented-economics-engineering, which sits alongside the vault's other independent-discovery threads (claim-reverse-mode-multiple-independent-discovery, claim-labview-max-independent-patch-cord-convergence) and its skeptical counterweight (claim-chandler-simultaneous-discoveries-are-incremental-repackagings).
Correction history.
- 2026-08-20 — This note previously stated the 1949 prototype cost ~£400 and modeled the economy to within ~2%, both sourced only to Wikipedia (Tier 4). A capture that read Phillips's own 1950 Economica paper, Nicholas Barr's 1988 LSE Quarterly history (LSE's institutional archives), and Doron Swade's 1995 Resurrection account found: the accuracy figure is Phillips's own stated ±4%, not ~2% (claim-phillips-1950-economica-states-hydraulic-computer-accuracy-as-4-percent; the ~2% figure traces to an uncited Barr aside, contradicted by Phillips and Swade — claim-barr-1988-uncited-2-percent-accuracy-figure-contradicted-by-phillips-and-swade); and the £400 figure is real in the archival record but prices LSE's 1950 second machine, not the 1949 Croydon prototype, which the same archive documents at £100 (claim-moniac-400-pound-figure-is-lse-second-machines-budget-not-original-prototype). Body corrected above. Source: 10-inbox/raw/2026-08-20-do-the-moniacs-400-build-cost-and-2.md.
Source
“The MONIAC was created in 1949 by Bill Phillips to model the national economic processes of the United Kingdom, using fluid logic — coloured water flowing through transparent tanks and pipes to represent money moving through the economy. (Tier-4 paraphrase — exact primary wording not yet obtained.)”