Arthur Doodson: The Man Who Weighed the Tide
Profile of Arthur Thomas Doodson (1890–1968): the Bidston mathematician whose rigorous analysis still runs inside every tide app on your phone.
Mechanical oceanography · 1872–1968
How gears predicted the sea.
Before computers, harbours worldwide depended on brass machines full of gears, shafts, and pulleys that added up the moon and sun — and drew tomorrow's tide. This archive reconstructs how they worked, who built them, and where you can still see them.
Thirty gears, one ocean
I am Daniel, an independent researcher. For this archive I study observatory records, engineering papers, and surviving machines, then redraw every mechanism as hand-coded SVG so you can see — not just read — how prediction worked.
Latest research
Friction, Backlash, and Wire Stretch: Where Analogue Error Lived
No rounding error — but plenty of drag. How friction, gear backlash, and wire stretch set the accuracy floor every brass predictor lived with.
Women Computers of the Tide Offices
The hidden workforce of brass prediction: the women who analysed records, checked machine output, and compiled the tide tables sailors trusted.
Build a Cardboard Harmonic Adder: A Weekend Project
A working two-constituent tide adder from cardboard, string, and washers: feel harmonic summation in your hands in one weekend afternoon.
How to Read a Printed Tide Table Like a 1920 Navigator
From machine-drawn roll to pocket table: how clerks compiled high and low waters, what the columns mean, and how to use a historic table today.
The Pulley Adder: How Wires Add Waves
The cleverest part of every tide machine: how floating pulleys sum a dozen crank motions onto one wire, and why friction was the eternal enemy.
Start with the pillars
- What Is a Tide-Predicting Machine? A Complete Beginner's Guide
- How Harmonic Analysis Predicts Tides: From Kelvin to Doodson
- History of Mechanical Tide Predictors, 1872–1968
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