History of the horse in Britain drawn by two horses, the "Dutch plough", was used in eastern England; this was followed in 1730 by the lightweight Rotherham plough, an unwheeled, or "swing" plough. It was advertised as reducing ploughing times by a third, or using a third less horsepower for the same ploughing time. The improved seed drill and horse-hoe were invented by Jethro Tull in 1731; but it took more than 100 years for these designs to come into common use. The earliest horse-powered threshing machines, which were installed permanently in barns, were developed towards the end of the 18th century. The use of fast
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