Elevation

The elevation of a geographic location is its height above or below a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface (see Geodetic system, vertical datum). Elevation, or geometric height, is mainly used when referring to points on the Earth's surface, while altitude or geopotential height is used for points above the surface, such as an aircraft in flight or a spacecraft in orbit, and depth is used for points below the surface.

Less commonly, elevation is measured using the center of the Earth as the reference point. Due to equatorial bulge, there is debate as to which of the summits of Mt. Everest or Chimborazo is at the higher elevation, as the Chimborazo summit is further from the Earth's center, while the Mt. Everest summit is higher above mean sea level.

Maps and GIS

A topographical map is the main type of map used to depict elevation, often through use of contour lines. In a Geographic Information System (GIS), digital elevation models (DEM) are commonly used to represent the surface (topography) of a place, through a raster (grid) dataset of elevations. Digital terrain models are another way to represent terrain in GIS.

Anatomical terms of motion

Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relative to the anatomical position of the joints. Anatomists use a unified set of terms to describe most of the movements, although other, more specialized terms are necessary for describing the uniqueness of the movements such as those of the hands, feet, and eyes.

In general, motion is classified according to the anatomical plane it occurs in. Flexion and extension are examples of angular motions, in which two axes of a joint are brought closer together or moved further apart. Rotational motion may occur at other joints, for example the shoulder, and are described as internal or external. Other terms, such as elevation and depression, refer to movement above or below the horizontal plane. Many anatomical terms derive from Latin terms with the same meaning.

Elevation (ballistics)

In ballistics, the elevation is the angle between the horizontal plane and the direction of the barrel of a gun, mortar or heavy artillery. Originally, elevation was a linear measure of how high the gunners had to physically lift the muzzle of a gun up from the gun carriage to hit targets at a certain distance.

Pre-WWI and WWI

Though early 20th-century firearms were relatively easy to fire, artillery was not. Before and during World War I, the only way to effectively fire artillery was plotting points on a plane.

Most artillery units seldom employed their cannons in small numbers. Instead of using pin-point artillery firing they used old means of "fire for effect" using artillery en masse. This tactic was employed successfully by past armies.

But changes have been made since past wars and in World War I, artillery was more accurate than before, although not as accurate as modern artillery guns. The tactics of artillery from previous wars were carried on, and still had similar success. Warships and battleships also carried large caliber guns that needed to be elevated to certain degrees to accurately hit targets, and they also had the similar drawbacks of land artillery.

Rapid (disambiguation)

A rapid is a section of a river with turbulent water flow.

Rapid may also refer to:

Places

Sports clubs

Traffic

Other

Rapid (brig)

The Rapid was a brig of 161 tons, remembered as the ship which brought William Light's surveying party to the new colony of South Australia.

History

The Rapid was built in 1826 at Yarmouth, and featured a carved figurehead in the shape of a greyhound.

South Australia

She was purchased by the board of commissioners of the South Australian Company to send out on their first fleet to establish the Colony of South Australia and the city of Adelaide. The company added a deck for passenger exercise, but as the height between decks was 4'1" (1.25 m), it was hardly luxurious. On 1 May 1836, the Rapid left Blackwall, and sailed down the English Channel under the command of Col. William Light, and reached Kangaroo Island on 17 August 1836.

Light's crew included Lieut. G. M. Field, R.N. (first officer), Lieut. (later Admiral) William S. Pullen (second officer), Lieut. R. Hill (third officer) and Thomas Woodforde (surgeon). Other members of the party were William Bell, W. Bradley, Robert Bush, William Chatfield, George Childs, William Clampton, John Duncan, William Freemantle, Edward Gandy, Marion Gandy, William Gandy, Thomas Gepp, Robert Goddard, William Hodges, William Jacob, William Lawes, James Lewis, George Mildred, Hiram Mildred, George Penton, and Robert G. Thomas, John Thorn, John Thorpe, William Tuckey.

HMS Nova Scotia (1812)

When HMS Maidstone and HMS Spartan captured the American privateer Rapid in 1812, the Royal Navy took her into service as the 14-gun gun-brig HMS Nova Scotia. She was renamed HMS Ferret in 1813 and sold in 1820.

Privateer Rapid

Rapid, of Portland, Maine, had two commanders, Captain W. Crabtree and Captain J. Weeks, during her career as a privateer. Rapid captured one ship, the Experience, and two brigs. The Experience's cargo was valued at US$250,000.

The owners of one brig ransomed her and Rapid sent the other, the St. Andrews, of eight guns and sailing in ballast, into Portland. Another report has Rapid capturing a barque St Andrews, of eight guns, that she sent into Portland. The ransomed vessel may have been the schooner Mary, of St Thomas, which Rapid ransomed as Rapid could not spare the men for a prize crew.Rapid apparently also captured the brig Pursuit, sailing from Poole to St. Andrews and the brig Tay, sailing from Dundee for Pictou, New Brunswick. Rapid sent both into Portland. Lastly, Rapid captured and burnt a British New Providence privateer, the Searcher, of one gun and twenty men.