Glossary: 40 Terms of Harmonic Tide Science
The working vocabulary of brass prediction: constituents, epochs, Doodson numbers, marigrams, and every jargon term decoded in plain English.
glossaryterminologyDoodson numbersreference
All articles (25)
Every piece is original research by Daniel, illustrated with hand-coded SVG. New entries appear as the archive grows. Browse by bench, or see where to start.
Guides
History of Mechanical Tide Predictors, 1872–1968
Ninety years of brass computers: from Kelvin's 1872 prototype through the American giants, Bidston rigour, German rivals, and the digital end.
historyKelvinBidstontimeline
How Harmonic Analysis Predicts Tides: From Kelvin to Doodson
The mathematics that made brass machines possible: constituents, least-squares analysis, and how Kelvin, Darwin, and Doodson turned chaos into prediction.
harmonic analysisM2Doodsonmathematics
What Is a Tide-Predicting Machine? A Complete Beginner's Guide
A plain-English introduction to mechanical tide predictors: what they were, how gears added the moon and sun, and why ports trusted them for 90 years.
beginnersharmonic analysisKelvinmechanisms
History
Tides at War: Prediction Machines, 1914–1945
How two world wars turned brass predictors into strategic assets: round-the-clock cranking, amphibious landings, and the tables that moved armies.
wartimehistoryamphibious landings20th century
Why the Machines Died: Digital Computers, 1960–1968
The quiet obituary of brass prediction: how stored-program computers beat gears on speed, cost, and flexibility between 1960 and 1968.
digital computers1960sobituaryhistory
How-It-Works
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.
errorfrictionbacklashaccuracy
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.
pulley addermechanismssummationfriction
Spring vs. Neap: Why the Range Breathes Every Fortnight
The fortnightly heartbeat of the tide: how the moon and sun take turns amplifying and cancelling each other, in plain English with a visual.
spring tidesneap tidesM2S2
Tide Staff vs. Tide Gauge vs. Tide Predictor: What's the Difference?
Three instruments, three jobs: the staff you read by eye, the gauge that records, and the predictor that foretells. How observation became prediction.
instrumentstide gaugetide staffobservation
Gear Ratios That Model the Moon: A Visual Primer
How toothed wheels approximate the 12.42-hour lunar period: compound trains, continued fractions, and the craft of the gear cutters explained visually.
gearsM2craftvisual primer
Why 37? The Harmonic Constituents M2, S2, K1, O1 in Plain English
Meet the waves inside every prediction: the big four constituents, their shallow-water children, and why America's Machine No. 2 stopped at 37.
constituentsM2S2Machine No.2
Machines
Tide Analysers: The Machines That Ran Backwards
Predictors foretell; analysers dissect. How the rarer reverse machines extracted harmonic constants from gauge records — and why few were built.
analysersharmonic analysisrare machinesmechanisms
German Gezeitenrechenmaschinen: The Forgotten Competitors
Hamburg's elegant answer to Kelvin and America: the German tide-calculating machines, their refined wire runs, and the engineers history overlooked.
GermanyHamburgGezeitenrechenmaschinenrivals
The Bidston Observatory Machines and Arthur Doodson
Liverpool's Bidston Observatory rebuilt tidal science: Doodson's least-squares rigour, 60+ constituents, and the quiet machines that predicted for hundreds of ports.
BidstonDoodsonLiverpoolleast squares
Inside the US Coast Survey Machine No. 2: 37 Components Explained
America's 37-constituent brass giant (1912): how Harris and Fischer scaled Kelvin's idea to world-record size, and what each bank of cranks did.
Machine No.2HarrisFischer37 constituents
How Lord Kelvin's First Tide Predictor Actually Worked
Inside the 1872 Légé-built prototype: ten cranks, one wire, and the first proof that brass could add the moon and sun into tomorrow's tide.
Kelvin1872prototypemechanisms
People
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.
DoodsonBidstonbiographymathematician
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.
human computerswomen in sciencetide officeshistory
Who Built the Machines? The Craftsmen Behind the Brass
Beyond Kelvin and Doodson: the instrument makers — White, Légé, Fischer — whose gear-cutting skill decided whether a predictor told the truth.
instrument makerscraftWhiteFischer
Practice
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.
DIYhands-onweekend projectpulley adder
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.
tide tablesnavigationhands-onclerks
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.
museumssurviving machinesvisiting guidecollections
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.
prediction rollstide tableshands-onarchives
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.
operatorscalibration1910hands-on