Industrial Revolution sectors of the economy. However, per-capita food supply in Europe was stagnant or declining and did not improve in some parts of Europe until the late 18th century. Industrial technologies that affected farming included the seed drill, the Dutch plough, which contained iron parts, and the threshing machine. Jethro Tull invented an improved seed drill in 1701. It was a mechanical seeder which distributed seeds evenly across a plot of land and planted them at the correct depth. This was important because the yield of seeds harvested to seeds planted at that time was around four or five. Tull's seed
Drill bit shank shank was common before 1850, and is still in production. At first, the tapered shank was just rammed into a square hole in the end of the drill. Over time, various chuck designs have been invented, and modern chucks can grasp and drive this shank effectively. It has been difficult to find a reference to the included angle of the taper, but 7 different bits were measured, and they all had an included angle of 8 ± 0.25 degrees. The straight shank is the most usual style on modern drill bits, by number manufactured. The whole of the drill bit,