In 1923, a Frenchman named Franck Duroquier published the fourth edition of a manual assuming something modern readers would find astonishing: that an ordinary amateur, working at a kitchen table, could and should build every single component of a working radio receiver from raw materials. Not assemble a kit. Not solder a pre-designed board. Build.

The table of contents reads like a lost civilization's engineering curriculum:

IV. — APPAREILS D'ACCORD ET DE RÉGLAGE
1° Construction d'une bobine d'accord...
2° Construction d'un transformateur d'induction...
3° Construction de selfs...
4° Construction de condensateurs variables...
5° Bobines à plusieurs couches de fil...
VI. — RÉCEPTION DES ONDES ENTRETENUES
1° Construction de tikkers...
2° Construction d'un hétérodyne...

Chapter III instructs the reader on the "Construction et utilisation" of detectors and vacuum tubes — yes, hand-building vacuum tubes. Chapter IV walks you through winding your own inductors and rolling your own variable capacitors. Chapter VI covers the "tikker," a mechanical interrupter that let you demodulate continuous-wave signals in the pre-vacuum-tube era by chopping them into audible clicks.

The book was distributed by Masson et Cie, a prestigious Parisian scientific publisher (still around, now part of Elsevier). Duroquier had previously written La Télégraphie sans fil pour tous, which received a Ministerial subscription — meaning the French government thought so highly of amateur radio education that it bought copies for public libraries and normal schools.

What's genuinely lost here isn't the specific circuits — you can still find those. It's the assumption that a curious amateur ought to understand their communications equipment at the level of vacuum physics and electromagnetic tuning. In 1923, "radio" meant you knew how a coupling coefficient worked because you had wrestled with one at your workbench.

Is any of this still valid? Absolutely. Modern amateur radio operators still occasionally wind their own toroidal inductors; the physics of a variable capacitor hasn't changed since Duroquier drew his "dessins, plans et croquis originaux." A homemade crystal radio built to these 1923 specifications will still pull AM broadcasts out of the air today, powered by nothing but the radio waves themselves. Vintage "tikker" demodulators are occasionally rebuilt by hobbyists exploring pre-1920 wireless history.

The connection to today is uncomfortable. We're surrounded by devices — phones, WiFi routers, Bluetooth earbuds — whose internals are literally sealed against user access. The 1923 amateur understood their radio the way a modern user understands... nothing they own. Duroquier's readers were expected to be their own tech support, their own manufacturer, and their own R&D department. The right-to-repair movement is trying to claw back a fraction of what was simply assumed a century ago.