The Phillips Machine, also called the Moniac, or Monetary National Income Analogue Computer, was created in 1949 by the New Zealand economist Bill Phillips. It churns out solutions to equations, using hydraulics instead of differential calculus to calculate the answers. It is a simple computer, although not quite as simple as one might assume. It can solve nine differential equations simultaneously and within a few minutes — a feat that is impossible by hand. Even in the 1950s, economic models were worked out by rooms full of human ‘computers’. It would be years before digital computers could support economic models as complex as the Moniac’s.
Phillips’ childhood
Alban William Phillips was born in 1914 on a small dairy farm in Te Rehunga, a rural area of New Zealand. His father, Harold, was ahead of his time, equipping the farm with a flush toilet, a waterwheel-powered generator, and electric lighting—long before these became common in neighbouring farms. Harold also nurtured his children’s curiosity, teaching them how to build crystal radios, zoetropes, and various toys.
Academic start
After spending his childhood in New Zealand, Phillips later moved to London and enrolled at London School of Economics.
When World War II broke out, he joined the Royal Air Force, which sent him back to the Pacific. As a RAF engineer, he worked to modernise outdated aircraft intended to defend British-held Singapore from Japanese forces.
However, after Singapore fell, Phillips was captured and spent three years in a Japanese prisoner-of-war camp. Despite the inhumane conditions, his ingenuity never wavered. To boost morale and keep fellow prisoners informed, he built hidden radios, including one small enough to be concealed in the heel of his shoe. He also designed makeshift immersion heaters, enabling prisoners to prepare hundreds of cups of tea each evening. The guards never realised why the camp’s lights flickered at night. His exceptional out-of-the-box thinking during these challenging years ultimately paved the way for his groundbreaking engineering innovations in later life.
Post-World War II
After the war, Alban William Phillips returned to London and resumed his studies at the London School of Economics. Initially enrolled in sociology, he soon became captivated by the mathematical equations emerging in the new field of macroeconomics. Fascinated by their engineering-like precision, he began skipping his sociology lectures, retreating instead to his landlady’s garage in Croydon.
In his garage, he set about constructing a hydraulic model of the equations his lecturers were sketching on blackboards. One of those lecturers was James Meade. Rather than dismissing Phillips—who had practically abandoned sociology—Meade was intrigued by his unconventional approach. With Meade’s support, Phillips was given the opportunity to present his remarkable invention at the prestigious Robbins seminar in late 1949.
The very first demonstration
As the demonstration began, Phillips worked behind the intricate array of Perspex pipes and tanks, activating a pump salvaged from a Lancaster bomber. Pink-dyed water gushed into a top reservoir before cascading down through the system, mimicking the flow of money in an economy. As the machine worked flawlessly, the assembled professors were stunned. The demonstration was a resounding success. Within minutes, the room was filled with excitement. Phillips had created the first-ever computer model of a national economy. His invention, initially called the Monetary National Income Analogue Computer (Moniac), became better known as the Phillips Machine. Using hydraulics rather than differential calculus provided tangible, visual solutions to complex economic equations—an engineering marvel that forever changed the way economists approached their field.
How the machine works
The Moniac was a simple computer, but not as simple as one might think. It could simultaneously solve nine differential equations within minutes—an impossible task if done by hand. Even in the 1950s, economic models were calculated manually by rooms full of human "computers", primarily women armed with paper and calculators, much like a mathematical version of a typing pool. It would take years before digital computers could handle economic models as complex as the Moniac’s.
Phillips built 14 of these machines, most of them Mark II Moniacs, which were improved and expanded versions of the original. Standing seven feet tall and four to five feet wide, the Mark II appears both imposing and quaint by today’s standards.
The Phillips Machine at Erasmus School of Economics
Out of the 14 machines Phillips has made, one ended up at the Netherlands School of Economics, the predecessor of Erasmus School of Economics. It is an absolute showpiece in the university’s heritage collection, standing in the hall of the Theil building. The Municipality of Rotterdam donated the Phillips Machine for educational purposes on the fortieth anniversary of the Netherlands School of Economics in 1953.
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This item is part of Backbone Magazine 2025. The magazine can be found in E-building or Theil-building for free. Additionally, a digital copy is available here. Backbone is the corporate magazine of Erasmus School of Economics. Since 2014, it is published once a year. The magazine highlights successful and interesting alumni, covers the latest economic trends and research, and reports on news, events, student and alumni accomplishments.
