Clock position

These quarters may have specialized names, such as bow and stern for a vessel, or nose and tail for an aircraft.

In this analogy, the observer imagines the vessel located on a horizontal clock face with the front at 12:00.

Neglecting the length of the vessel, and presuming that he is at the bow, he observes the time number lying on the line of sight.

This is a system of denoting impromptu relative bearing widely used in practical navigation to give the position of an observed object readily and comprehensibly.

The angular distance between adjacent clock numbers is 30 degrees, a round unit that simplifies mathematical juggling.

A quick clock number can be shouted by a lookout, whereas after a calculation and comparison of compass points, which might be unknown anyway, it might be too late for the vessel to avoid danger.

[2] The convention is that of analytic geometry: the y-axis at zero degrees is the longitudinal axis of the vehicle.

[3] These circles are not to be confused with latitude and longitude, or with any sort of compass reading, which are not relative to the vehicle, but to the magnetic and spin axes of the Earth.

For example, clock position on a 12-hour analog watch can be used to find the approximate bearing of true north or south on a day clear enough for the sun to cast a shadow.

The technique takes a line of sight (LOS) on the visible sun, or on the direction pointed to by a shadow stick, through the hour hand of the watch.

If the sun is in the southern half of the sky, the zenith bearing points true south; if northern, north.

It can be corrected to solar time, but LOS on a watch is generally too imprecise to make the trouble worth the effort.

[4] In World War II aircraft pilots needed a quick method of communicating the relative position of threats, for which the clock system was ideal.

The pilots needed a vertical dimension, so they supplemented the clock position with the word high or low to describe the vertical direction; e.g., 6 o'clock high means behind and above the horizon, while 12 o'clock low means ahead and below the horizon.

For airplanes in rapid maneuvers, air traffic controllers will issue the eight cardinal compass points instead.

[6] In 1916, J.B. Plato devised a clock system to identify farms around reference points in rural areas.

A clock face was imagined centered on a rural community with 12:00 pointing true north.

A clock face is considered imposed over each breast, left and right, centered on the alveolar region, with the positions shown around it.

The ball will only run true when hit from the high or low points; otherwise, its course will break, or bend on the slope.

[9] An article in the Journal of Applied Microscopy for 1898 recommends the use of a polar coordinate system in the form of a clockface for recording the positions of microscopic objects on a slide.

Additionally, the error could also occur when the radar traffic information is issued while the aircraft is changing course.

[11] Although the raw clock position is invaluable or indispensable in many circumstances requiring rapid response, for ordinary careful navigation it is not sufficiently precise.

Tablets of different periods reveal the development of a sexagesimal numbering system from decimal and duodecimal systems, which reveals itself in the construction of unique symbols for numerals 1-59 from natural finger decimals (ten fingers, ten symbols).

Why they developed this system is a matter for academic debate, but there are multiple advantages, including division by several factors, offering several possible subdivisions, one of which is by 12's.

For reasons that are not clear, the Mesopotamians adopted a standard of 12 hours per day for their first-order digit.

Their day, however, was designed for measurement on their most ancient and widely used timepiece, the sundial, which showed only daylight hours.

Daylight was the time between sunrise and sunset, each of those being defined as the appearance or disappearance of the top rim of the sun on the horizon.

Englund distinguishes two main types of system: the cultic, in which the events of the seasonal calendar assume religious significance, and are perpetuated for religious reasons, and a second, new type, the state, defined by an administration that needed to standardize its time units.

The state administrators had perceived that the sun advances at a uniform rate no matter what the season.

[19] This assignment was the creation of the 360-degree circle, as the degree went from being a time division to an angular distance of rotation.

Points of a 12-hour clock
Horizontal sundial of 1812 matching the clock positions in Roman numerals on the outside dial to the points of a compass rose on the inside dial. The XII position is true north.
Traffic information would be issued to the pilot of aircraft “A” as 12 o'clock. The actual position of the traffic as seen by the pilot of aircraft “A” would be 2 o'clock. Traffic information issued to aircraft “B” would also be given as 12 o'clock, but in this case, the pilot of “B” would see the traffic at 10 o'clock. [ 11 ]
Roman basin sundial, a Mesopotamian type. The pointer casts a shadow over the engraved hour lines in the basin. The hours are numbered I-XII, running from the first hour of the day on the left to the last on the right. The pointer is set at meridies, “mid-day,” which is at 6:00. The hours are “seasonal;” that is, the number of degrees in an hour depends on the day of the year. 6:00 is intended to be a true bearing; that is, at 12:00 solar time the shadow over the VI line must point due north or south.