Civilization manualBook 1: From Bare Hands to Steam and Electricity765 entries · 23 phases · 100 years
The Island
Phase 10 — Blast furnace, coal, cast iron and rolling  /  About year 21
10.05

Mine ventilation

a second shaft and air doors draw fresh air through the workings

MakingYear 21Stands on 124 earlier

AWhat it needs

Needs 124 other products in all, 2 of them directly.

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