Course

Course can refer to:

Course (sail)

In sailing, a course is the lowermost sail on a mast.

This term is used predominantly in the plural to describe the lowest sails on a square rigged vessel, i.e., a ship's courses would be the foresail, mainsail, and, on the rare occasions in which one is shipped, mizzen.Gaff-rigged vessels may use the term (for the lowest sail rigged aft of each mast), but are more likely to refer simply to a mainsail, foresail, etc. A Bermuda- or lateen-rigged yacht, whether sloop, cutter, ketch or yawl, would not usually be described as having a course.

References

Course (navigation)

In navigation, an object's course is the direction over the ground along which the object is currently moving.

Course, track, route and heading

The line connecting the object's consecutive positions on the ground is referred to as the ground track. The track the object was intended to follow is called the route. For ships and aircraft, the route is represented by the great circle line that connects the previous waypoint with the next waypoint. The responsibility of a navigator is to make the track coincide as much as possible with the route. The direction of the route is called the route course. "Course" exceptionally, and arguably erroneously, may also refer to the route, such as in a course deviation indicator, in which case it no longer constitutes an angle but rather a line. The direction of the great circle line that runs from the current position to the next waypoint is called the course to steer, or the bearing to that waypoint. The tracking angle is the angle between the course to steer and the course. The heading is the direction to which the "nose" of the object is pointing, its orientation.

Nail

Nail or Nails may refer to:

In biology

Objects

Arts and entertainment

People

Businesses

Nail (fastener)

In woodworking and construction, a nail is a pin-shaped object of metal (or wood, called a treenail or "trunnel") which is used as a fastener, as a peg to hang something, or sometimes as a decoration. Generally nails have a sharp point on one end and a flattened head on the other, but headless nails are available. Nails are made in a great variety of forms for specialized purposes. The most common is a wire nail. Other types of nails include pins, tacks, brads, and spikes.

Nails are typically driven into the workpiece by a hammer, a pneumatic nail gun, or a small explosive charge or primer. A nail holds materials together by friction in the axial direction and shear strength laterally. The point of the nail is also sometimes bent over or clinched after driving to prevent pulling out.

History

The history of the nail is divided roughly into three distinct periods:

Nail (relic)

Relics that are claimed to be the Holy Nails with which Christ was crucified are objects of veneration among some Christians, i.e., among Catholics and the Eastern Orthodox. In Christian symbolism and art they figure among the Instruments of the Passion or Arma Christi, the objects associated with Jesus' Passion. Like the other Instruments the Holy Nails have become an object of veneration among many Christians and have been pictured in paintings and supposedly recovered.

When Helena, mother of Constantine the Great discovered the True Cross in Jerusalem, the legend was told by and repeated by Sozomen and Theodoret that the Holy Nails had been recovered too. Helena left all but a few fragments of the Cross in the Basilica of the Holy Sepulchre in Jerusalem, but returned with the nails to Constantinople. As Theodoret tells it in his Ecclesiastical History, chapter xvii,

The mother of the emperor, on learning the accomplishment of her desire, gave orders that a portion of the nails should be inserted in the royal helmet, in order that the head of her son might be preserved from the darts of his enemies. The other portion of the nails she ordered to be formed into the bridle of his horse, not only to ensure the safety of the emperor, but also to fulfil an ancient prophecy; for long before Zechariah, the prophet, had predicted that 'There shall be upon the bridles of the horses Holiness unto the Lord Almighty.