Four-centred arch

A four-centred arch, also known as a depressed arch or Tudor arch, is a low, wide type of arch with a pointed apex. It is much wider than its height and gives the visual effect of having been flattened under pressure. Its structure is achieved by drafting two arcs which rise steeply from each springing point on a small radius, and then turning into two arches with a wide radius and much lower springing point.

This type of arch, when employed as a window opening, lends itself to very wide spaces, decoratively filled with many narrow vertical mullions and horizontal transoms. The overall effect produces a grid-like appearance of regular, delicate, rectangular forms with an emphasis on the perpendicular. It is also employed as a wall decoration in which arcade and window openings form part of the whole decorative surface.

The style, known as Perpendicular Gothic, which evolved from this treatment, is specific to England, and is very similar to contemporary Spanish style in particular. It was employed to great effect through the 15th century and first half of the 16th, as Renaissance styles were much slower to arrive in England than in Italy and France.

It can be seen notably at the East End of Gloucester Cathedral where the East Window is said to be as large as a tennis court. There are three royal chapels and one chapel-like Abbey which show the style at its most elaborate: King's College Chapel, Cambridge; St George's Chapel, Windsor; Henry VII's Chapel at Westminster Abbey, and Bath Abbey. However, numerous simpler buildings, especially churches, built during the wool boom in East Anglia, are demonstrate the style.

Use in English architecture
In English architecture, it is often known as a Tudor arch, as it was a common architectural element during the reign of the Tudor dynasty (1485–1603). The Gothic period's pointed arch was blunted into the flattened Tudor arch. The Tudor arch, placed over the oriel window, or a bay window supported on a bracket or corbel, was a striking window design of the Tudor period.

This type of arch, applied to the window opening, can occupy a wide space, filled with vertical posts dividing the window into parts and horizontal overhangs. The overall effect gives the impression of a delicate lattice emphasizing the perpendicular and vertical layout. As a wall decoration, the arcade, together with the window opening, make up the entire decorative composition. This style, known as Perpendicular (perpendicular, vertical), is characteristic of Great Britain, although it is very similar to the contemporary style dominating in Spain. It was used in the fifteenth and first half of the Sixteenth century, because the style of the Renaissance in England appeared later than in Italy or France.

This arch was used on the western wall of the Gloucester cathedral, where the Great East Window is the size of a tennis court . There are also three famous royal chapels and abbeys: King's College Chapel in Cambridge, St George's Chapel in Windsor Castle, Chapel of Henry VII in Westminster Abbey and Bath Abbey. These bows can also be found in many smaller churches, especially those built during the prosperity of the wool industry in East Anglia in the fifteenth century, because that's where the ships exporting wool from England came. During the voyage to England, the ships were used to import bricks, which was then a luxury material .

The Tudor Arch was also placed in a bay window, based on a sword or console, which was a special architectural achievement of the Tudor period .

Gloucester Cathedral, west front, window in form of a Tudor arch
King's College Chapel, Cambridge, window in form of a Tudor arch
Front doorway to Sutton Place, Surrey, c. 1525, in shape of Four-centred Tudor arch, imaginary Tudor scene by Nash, c. 1840
St. George's Chapel, Windsor, east window

Use in Polish architecture
Arches similar to the Tudor arc were used in Poland, among others in the St. Mary's church in Gryfice and the church of St. Mary Magdalene in Czersk.

St. George's Chapel, Windsor Castle, eastern window in the form of a Tudor arc. Scene of the marriage of the Prince of Wales and Alexandra, 1863
Ejwan in Khajr ul-Manazil, Delhi, India : a sharp lowered bow
Ejwan in Majdah Gandjali Khan, Kerman, Iran : a sharp lowered bow

Use in Islamic architecture
The four-centred arch is widely used in Islamic architecture, especially that of Persianate cultures. For example, almost all iwans use this type of arch.

Source From Wikipedia