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 for about £400, scrounging war-surplus parts including pieces of scrapped Lancaster bombers, and it was said to reproduce real UK economic data to within roughly 2%. These two figures are [unverified-quant]: they rest only on the Tier-4 Wikipedia article, and quantitative claims require a primary source under the vault's sourcing floor. See question-verify-moniac-cost-and-accuracy-figures. 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).