Aincrad's Industrial Technology

In Aincrad, where wheat and barley are the staple crops, the windmill was invented fairly early as a means of milling the grains using the strong winds that buffeted the airborne land. Over the course of millennia spent in the air, other inventions sprung up, like water mills, eyeglasses, clocks, the three-field system of farming, reinforced buildings, and chimneys. Even black gunpowder was created, but due to the magic binding Aincrad, which prevents any manner of projectile weapon, it can only be used for mining.