The Century Engine

The Century Engine is a 12-meter-tall, walk-in mechanical computer that will accurately track and display the positions of the sun, moon, and planets, as well as key ecological metrics (temperature, CO2, sea level) through purely analog means. It is designed to operate continuously for 100 years with zero human intervention, using only the natural forces of gravity, thermal expansion, and atmospheric pressure. The structure is a toroidal frame of cast basalt and stainless steel, housing thousands of gears, linkages, and fluid-filled capillaries. A central heat engine uses daily temperature cycles to wind a mainspring, which powers the computation. The output is physical: large dials, rotating sculptures, and engraved stone tablets that update incrementally. Every component is oversized, redundant, and lubricated with a solid-film graphite coating. The entire machine is housed in a sealed, argon-filled chamber to prevent oxidation and microbial growth. The project was conceived as a foil to the disposable electronics of the 21st century—a statement that hardware can be designed for centuries, not years.

Modern infrastructure and electronics are designed for short lifespans (5-10 years), creating a culture of planned obsolescence and e-waste. There is no public, durable, long-term physical record of our planet's changes that is immune to digital decay. Existing long-term clocks (e.g., the Clock of the Long Now) are either too abstract or rely on rare materials. A need exists for an accessible, educational, and aesthetically powerful artifact that embodies the principle of thinking in centuries, not quarters.

• Compute and display the orbital positions of all eight planets with 0.1 degree accuracy for 100 years
• Track Earth's axial precession and orbital eccentricity changes over a century
• Measure and record daily temperature, atmospheric pressure, and sea level using mechanical sensors
• Automatically wind its own mainspring using diurnal temperature cycles
• Operate with zero human maintenance for the full 100 years
• Be made entirely from materials that do not corrode or degrade under argon atmosphere
• Provide a public, interactive viewing platform where visitors can read the current and historical data
• Survive a 1-in-100-year seismic event without stopping

• Not a digital computer; no electricity, no electronics, no microcontrollers
• Not a replacement for modern scientific instruments; accuracy is educational, not research-grade
• Not designed to be disassembled or repaired; it is sealed for the century
• Not a time capsule; it does not store messages or art, only data
• Not a clock in the conventional sense; it does not show hours and minutes, only astronomical and planetary time

• Structure: Cast basalt, titanium alloy (Ti-6Al-4V) for load-bearing components, stainless steel (316L) for non-structural parts
• Gears and linkages: Silicon nitride ceramic gears (zero wear, no lubrication needed) with titanium shafts
• Springs: Nickel-titanium (Nitinol) shape-memory alloys for temperature-driven actuation
• Bearings: Laminated carbon-carbon composite bushings (self-lubricating)
• Working fluid: Deionized water in sealed capillaries (used in thermometers and barometers)
• Housing: Argon gas at 1.1 atm in a welded titanium vessel with a single, resealable access port
• Computational mechanism: A network of differential gears, cams, and linkages that model Kepler's laws and Newtonian gravity via analog computation

The Century Engine is a toroidal (donut-shaped) structure 12m in diameter and 3m thick. The outer ring houses the planetary compute module: a series of nested gear trains each representing a planet's orbital period relative to Earth's. The inner ring contains the celestial sphere display: a rotating array of polished stone spheres (representing planets) driven by the compute module. At the center is the thermal engine: a stack of bimetallic disks that contract and expand with daily temperature changes, winding a mainspring. Energy is stored in a constant-force spring and distributed to the gear trains via a series of escapements. Sensors are purely mechanical: a mercury-free Fahrenheit thermometer (using a sealed water/alcohol mix) drives a pen on a rotating stone cylinder; a bellows barometer records atmospheric pressure; a mechanical sea-level gauge (a float in a long tube connected to a distant tide gauge) is transmitted via a system of levers and chains. Outputs are physical: large dials (2m diameter) made of engraved stone pointers on ceramic faces, and a 10m-long stone scroll that advances 1mm per day, on which the recordings are etched by a sapphire stylus. The entire assembly is shock-isolated by a system of titanium springs resting on a basalt foundation.

• Seismic activity: A major earthquake could crack the basalt structure or dislodge gears; mitigated by base isolation and flexible couplings
• Material fatigue: Over 100 years, even ceramics can show microcracks; mitigate by using compressive loading only and safety factors of 5x
• Thermal cycling: Daily expansion/contraction could cause misalignment; mitigated by using materials with matched thermal expansion coefficients
• Argon leakage: Loss of inert atmosphere could cause corrosion; mitigate by using all-ceramic seals and a small reservoir of argon compresses to 1.1 atm for the full century
• Vandalism: Public access might lead to damage; mitigated by placing the display dials behind sapphire glass and limiting visitor touchpoints
• Funding: Estimated cost $50M; likely too expensive for a public art project; never secured philanthropic or government backing

• Can the temperature of the site be guaranteed between -20°C and 50°C for 100 years given climate change? The thermal engine relies on a minimum 10°C diurnal swing; if this vanishes (e.g., due to cloud cover or greenhouse warming), the mainspring may not wind enough.
• The analog planetary computer uses a series of approximations; do these drift over a century beyond the 0.1° accuracy goal? A full simulation is needed.
• How to test without accelerating time? We built a 1:10 scale model that ran for 3 years, but 100-year behavior is still uncertain.
• Should the site be in a geologically stable region (e.g., Finland) or more accessible but riskier?

Funding never materialized—the $50M price tag scared off philanthropists who wanted a 5-year impact, not a century. The team (three engineers, a clockmaker, and a materials scientist) disbanded after two years of prototyping, as life pulled them in different directions. The scale model still sits in a garage in Zurich, running smoothly.

The project was inspired by Danny Hillis' Clock of the Long Now and the Feynman Lectures on computation. Key insight: analog computing with gears is beautifully durable but insanely hard to make accurate over decades. The thermal engine was the most novel part—it works like a mechanical heart. During prototyping, we discovered that silicon nitride gears running under argon develop a burnished surface that actually reduces friction with time. A full patent was filed (US20230123456A1) but never pursued.