Crowmarsh Gifford Norman. A north transept with a pointed arch was added in about 1200. The building was restored in 1836 and 1868. In 1139 King Stephen built a wooden fort in Crowmarsh, the first of a series built in opposition to Wallingford Castle, which supported his cousin Matilda during the civil war known as The Anarchy. The forts were probably dismantled as a result of the Treaty of Wallingford of 1153. The castle at Crowmarsh consisted of a wide ditch surrounding an enclosure measuring . In 1701 agriculturist Jethro Tull invented his revolutionary seed drill here. In 1770 nearby Mongewell Park
Drill bit application. Many hard materials, such as carbides, are much more brittle than steel, and are far more subject to breaking, particularly if the drill is not held at a very constant angle to the workpiece; e.g., when hand-held. General-purpose drill bits can be used in wood, metal, plastic, and most other materials. The twist drill bit is the type produced in largest quantity today. It comprises a cutting point at the tip of a cylindrical shaft with helical flutes; the flutes act as an Archimedean screw and lift swarf out of the hole. The twist drill bit was invented by