FUN FACT ONE!!! 1) Many of the workman’s tools we use today were invented during the Roman Age or even before. Rybczynski explores the histories of several other tools such as the saw, the plane, the chisel, and the level. He discovers that all of these tools were invented during the Roman age if not before. The chisel, for example, dates from the Bronze Age. 2) The threading on a screw forms the shape of a helix, not a spiral. This is a common mistake. Rybczynski writes, “A spiral is a curve that winds around a fixed point with a continuously increasing radius…A helix…is a three-dimensional curve that twists around a cylinder at a constant inclined angle” (111). Spiral staircases form helixes, not spirals.