Seed drill further refined by Jethro Tull in 1701 in the Agricultural Revolution. However, seed drills of this and successive types were both expensive and unreliable, as well as fragile. Seed drills would not come into widespread use in Europe until the mid to late 19th century, when manufacturing advances such as machine tools, die forging and metal stamping allowed large scale precision manufacturing of metal parts. Early drills were small enough to be pulled by a single horse, and many of these remained in use into the 1930s. The availability of steam, and later gasoline tractors, however, saw the development of
Drill instructor Drill Instructor Ribbon, and the Army's Drill Sergeant Identification Badge. It may be taken offensively by U.S. Marine Corps Drill Instructors to be referred to as 'Drill Sergeants', which is strictly an Army term in the American military, just as Marines may take offense to being called "soldiers". This is considered to be a grievous insult if done intentionally. The only acceptable address of a drill instructor by a recruit is "sir", "ma'am" or "(senior) drill instructor (Rank) (last name)". At Officer Candidates School (OCS), candidates are instructed by Drill Instructors who have already served a tour at one of