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.
Practice
Hands-on skills for readers: setting up a prediction run the 1910 way, decoding inked prediction rolls and printed tide tables, building a cardboard harmonic adder in a weekend, and planning museum visits to see surviving machines turn.
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.
Where to See Surviving Machines Today (Museums Guide)
Every accessible tide-predicting machine I have verified: London, Washington, Munich, Hamburg, and Bidston legacy displays — plus what to look for.
Reading an Old Tide Prediction Roll: A Practical Guide
From ink curves to printed tables: how clerks read high and low waters off a machine-drawn roll, and how you can decode a surviving roll today.
How Operators Set Up a Prediction Run (Step by Step, 1910 Method)
A full working day with a spanner: how operators dialled a port's constants into dozens of crank pins before a single prediction could be drawn.
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