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A barrel vault, also known as a tunnel vault or a wagon vault, is an architectural element formed by the extrusion of a single curve (or pair of curves, in the case of a pointed barrel vault) along a given distance. The curves are typically circular in shape, lending a semi-cylindrical appearance to the total design. The barrel vault is the simplest form of a vault: effectively a series of arches placed side by side, i.e., one after another.

Barrel Vault

A barrel vault, also known as a tunnel vault or a wagon vault, is an architectural element formed by…

"A, B, C, tunnelings of the carpenter bee; E, the carpenter bee; D, a partition; F, teeth, magnified" — Goodrich, 1859

Carpenter Bee

"A, B, C, tunnelings of the carpenter bee; E, the carpenter bee; D, a partition; F, teeth, magnified"…

"Prior to the introduction of the cup and cone, a form of tunnel-head in which no valve or cone exists was employed. A hollow annular chamber BB is built in the upper portion of the stack, communicating by arched cavities A, A, A with the shaft, and also with the exit gas main C; a considerable fraction of the gases then passes out through the arched vavities when the materials are heaped up to the level of the charging door D. With small furnaces the wall between the shaft and the chamber B is made of past or wrought iron; in some cases the gas has been collected through a central tube in the axis of the shaft supported by groins springing from the shaft and the ore." — The Encyclopedia Britannica, 1893

Collecting Top

"Prior to the introduction of the cup and cone, a form of tunnel-head in which no valve or cone exists…

A groin vault or groined vault (also sometimes known as a double barrel vault or cross vault) is produced by the intersection at right angles of two barrel vaults. The word groin refers to the edge between the intersecting vaults; cf. ribbed vault. Sometimes the arches of groin vaults are pointed instead of round.

Groin Vault

A groin vault or groined vault (also sometimes known as a double barrel vault or cross vault) is produced…

An illustration of a group of people walking together in a tunnel with torches.

Group Walking in Tunnel

An illustration of a group of people walking together in a tunnel with torches.

Natural Bridge in Rockbridge County, Virginia is a geological formation in which Cedar Creek has carved a gorge of the limestone forming an arch 215 ft high with a span of 90 ft.

The Natural Bridge in Virginia

Natural Bridge in Rockbridge County, Virginia is a geological formation in which Cedar Creek has carved…

"A conduit or canal constructed, especially in a town or city, to carry off superfluous, water, soil, and other matters; a public drain. A, B, C, D, E forms used in London, Paris, and other European cities; F, G, H, I, J, K, L, special forms used in New York and other American cities. F shows a method of repairing with tiles at the bottom of an oval sewer. G, tile-bottomed sewer. H, barrel sewer...of wood bound with iron. I, a form used for large sewers. J, section of pipe sewer. K, half section of sewer having section similar to B, but also provided with a spandrel. L, the aqueduct form, used for large sewers only, it rests on a bed of concrete." —Whitney, 1889

Collection of Sewer Cross-Sections

"A conduit or canal constructed, especially in a town or city, to carry off superfluous, water, soil,…

This sign is used to indicate that a tunnel is located nearby.

Tunnel, Black and White

This sign is used to indicate that a tunnel is located nearby.

This sign is used to indicate that a tunnel is located nearby.

Tunnel, Color

This sign is used to indicate that a tunnel is located nearby.

This sign is used to indicate that a tunnel is located nearby.

Tunnel, Outline

This sign is used to indicate that a tunnel is located nearby.

This sign is used to indicate that a tunnel is located nearby.

Tunnel, Silhouette

This sign is used to indicate that a tunnel is located nearby.