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
Drill string the fish is based on the following logic: Drill string A drill string on a drilling rig is a column, or string, of drill pipe that transmits drilling fluid (via the mud pumps) and torque (via the kelly drive or top drive) to the drill bit. The term is loosely applied to the assembled collection of the drill pipe, drill collars, tools and drill bit. The drill string is hollow so that drilling fluid can be pumped down through it and circulated back up the annulus (the void between the drill string and the casing/open hole). The drill string is