The original technological revolution of the late Middle Ages, the eotechnic, was associated with the skilled craftsmen of the free towns, and eventually incorporated the fruits of investigation by the early scientists. It began with agricultural innovations like the horse collar, horseshoe and crop rotation. It achieved great advances in the use of wood and glass, masonry, and paper (the latter including the printing press). The agricultural advances of the early second millennium were further built on by the innovations of market gardeners in the sixteenth and seventeenth centuries—like, for example, raised bed horticulture, composting and intensive soil development, and the hotbeds and greenhouses made possible by advances in cheap production of glass.