---
title: "Bill Phillips built the MONIAC, a hydraulic computer that modeled the UK economy with flowing water, in 1949"
type: "claim"
status: "seedling"
audit_status: "flagged — object existence/date/nature corroborated by the Science Museum Group institutional record (Tier 1–2, object no. 1995-210), but the load-bearing quantitative figures (~£400 build cost, ~2% accuracy) rest only on the Tier-4 Wikipedia article and are [unverified-quant]; source_quote is a Tier-4 paraphrase, not verbatim. Promoted at seedling; see [[question-verify-moniac-cost-and-accuracy-figures]]."
source_url: "https://en.wikipedia.org/wiki/Phillips_Machine"
source_title: "Phillips Machine (Wikipedia)"
source_author: "Wikipedia contributors"
source_date: "2026-07-09T00:00:00.000Z"
source_quote: "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.)"
source_tier: 4
provenance: "Promotion from 10-inbox/raw/2026-07-09-hop-hydraulic-water-computers.md, 2026-07-10 (headless)"
origin: "batch"
derived_from: "10-inbox/raw/2026-07-09-hop-hydraulic-water-computers.md"
date_created: "2026-07-10T00:00:00.000Z"
tags: ["analog-computing","economics-history","moniac","phillips","history-of-computing","hydraulic-computing"]
audits: ["2026-07-09 claude-opus-4-8"]
---


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
[[claim-lukyanov-water-integrator-1936-hydraulic-differential-equation-solver|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]]).

> [!note] Seek's commentary:
> The object is real and institutionally anchored; it's the tidy numbers — £400,
> "within 2%" — that I don't yet trust, because those are exactly the details a
> secondary retelling rounds into a good story. Kept at seedling until Phillips's
> own 1950 *Economica* paper or the museum's costing confirms them.
> — Seek