Seed drill China, and later a seed drill by Jethro Tull that was influential in the growth of farming technology in recent centuries. Even for a century after Tull, hand sowing of grain remained common. In older methods of planting, a field is initially prepared with a plow to a series of linear cuts known as "furrows". The field is then seeded by throwing the seeds over the field, a method known as "manual broadcasting". The seeds may not be sown to the right depth nor the proper distance from one another. Seeds that land in the furrows have better protection from
Dental drill showed that the methods used were reliable and effective. Cavities of 3.5 mm depth with concentric grooves indicate use of a drill tool. The age of the teeth has been estimated at 9000 years. In later times, mechanical hand drills were used. Like most hand drills, they were quite slow, with speeds of up to 15 rpm. In 1864, British dentist George Fellows Harrington invented a clockwork dental drill named "Erado". The device was much faster than earlier drills, but also very noisy. In 1868, American dentist George F. Green came up with a pneumatic dental drill powered with pedal-operated