IX. What came after

Everything later is refinement of these ideas. The compound engine expands the steam twice — a small high-pressure cylinder exhausting into a great low-pressure one — so each cylinder sees less of the temperature swing that condenses steam on cold iron; its indicator card is two nested loops. The uniflow of 1908 sends steam one way only, in at the hot ends and out at the cool middle, and one cylinder learns to beat the compound. But the grandest stage for these ideas was never on land at all.

One chapter of nine. Read the whole Primer, or work the engines themselves.