All through the nineteenth century, the mostly employed varieties of screw head (that's, push kinds) were being very simple inside-wrenching straight slots and external-wrenching squares and hexagons. These were easy to device and served most programs sufficiently. Rybczynski describes a flurry of patents for different generate kinds during the 1860s https://stainlesssteelfixingssupp05059.thezenweb.com/the-ultimate-guide-to-wood-screw-68329868