What if the potato takes hold in Europe had gone differently?

A South American tuber becomes the calorie base of the northern European poor.

If it had gone differently: Northern Europe stays one bad grain harvest from famine; its population never surges.

1. 1740Europe's population boom, Without a surplus of hands and mouths, there is no cheap urban workforce waiting for the factories.
2. 1780The Industrial Revolution, Growth stays flat and Malthusian; most people alive in 1900 live about as their great-grandparents did.