Containers, fired pottery and the kiln, brick and tile, then glass.
Carry, store and cook — before you have pottery.
Needs first: Cordage, A cutting edge (Tools)
Make a fire-proof, waterproof, permanent container — and learn to control temperature.
Needs first: Fire, and keeping it (Energy), Containers
Make a standard, repeatable building unit — and something that will line a furnace.
Needs first: Pottery and the first kiln, Charcoal (Energy)
Make a transparent, chemically inert, formable solid.
Needs first: Lime, Charcoal (Energy), Brick and tile
Every guide, build, reference sheet and book reached from the steps above.
Fired clay is the first material a group makes that does not exist in nature: a rock with a shape you chose. Getting there is mostly patience — in the drying, and in the heating.
Level 3Density, stiffness, expansion and melting point for the materials the ladder makes, and what each number decides.
Level 1How to build a dwelling that stays dry and standing for thirty years from subsoil, stone and timber: choosing the method, setting out, foundations, walls, roof, drainage, and how to inspect, repair and maintain it.
Level 3What matter is made of and how it changes: amounts, gases, acids, the energy and speed of reactions, electrochemistry, and the reactions every industry on the ladder runs on.
The first machine that holds a temperature — pottery, brick and tile, and the training ground for every furnace above it.
A woven basket that fishes all night while you sleep — the highest return-per-hour food gear in tier 0.
A fireplace that throws its heat into the room and a lined flue that takes every trace of smoke out of the house: the part of a house most likely to burn it down or poison the people in it.
Burn limestone into quicklime — mortar, plaster, whitewash, flux, tannery liquor and soil correction, from one shaft.
A glass bead the size of a pinhead magnifies 150–350 times: enough to see yeast, blood cells and the larger bacteria that cause disease.
Two lenses in a tube: a 1-metre objective and a 25 mm eyepiece give 40×, enough to see Jupiter's moons and the phases of Venus.
Drawn overview sheets, each with its corrections printed under it. They orient; they are never the thing you identify from.
