Points of the compass

thumb|upright=1.45|32-point [[compass rose]]

The points of the compass are a set of horizontal, radially arrayed compass directions (or azimuths) used in navigation and cartography. A compass rose is primarily composed of four cardinal directions—north, east, south, and west—each separated by 90 degrees, and secondarily divided by four ordinal (intercardinal) directions—northeast, southeast, southwest, and northwest—each located halfway between two cardinal directions. Some disciplines such as meteorology and navigation further divide the compass with additional azimuths. Within European tradition, a fully defined compass has 32 "points" (and any finer subdivisions are described in fractions of points).

Compass points or compass directions are valuable in that they allow a user to refer to a specific azimuth in a colloquial fashion, without having to compute or remember degrees.

Designations

The names of the compass point directions follow these rules:

8-wind compass rose

thumb|8-wind compass rose

The four cardinal directions are north (N), east (E), south (S), west (W), at 90° angles on the compass rose.
The four intercardinal (or ordinal) directions are formed by bisecting the above, giving: northeast (NE), southeast (SE), southwest (SW), and northwest (NW). In English and many other tongues, these are compound words. Different style guides for the four mandate spaces, dashes, or none.
In Bulgarian, Catalan, Czech, Danish, Dutch, English, Esperanto, French, Galician, German, Greek, Hungarian, Ido, Italian, Japanese (usually), Macedonian, Norwegian (both Bokmal and Nynorsk), Polish, Portuguese, Romanian, Romansch, Russian, Serbian, Croatian, Spanish, Swedish, Ukrainian, and Welsh the part meaning north or south precedes the part meaning east or west.
In Chinese, Vietnamese, Gaelic, and less commonly Japanese, the part meaning east or west precedes the other.
In Estonian, Finnish, Breton, the "Italianate system" (see section "Traditional Mediterranean compass points" below), and many South Asian and Southeast Asian languages such as Telugu, the intercardinals have distinct words.
in NE quadrant: north by east (NbE), northeast by north (NEbN), northeast by east (NEbE), and east by north (EbN);
in SE quadrant: east by south (EbS), southeast by east (SEbE), southeast by south (SEbS), and south by east (SbE);
in SW quadrant: south by west (SbW), southwest by south (SWbS), southwest by west (SWbW), and west by south (WbS);
in NW quadrant: west by north (WbN), northwest by west (NWbW), northwest by north (NWbN), and north by west (NbW)
All of the points in the 16-wind compass rose plus the sixteen quarter-winds together form the 32-wind compass rose.
If breaking down for study/signalling the subcomponents are called the "principal" followed by the "cardinal" wind/direction. As a mnemonic (memory device), minds familiar encode the meaning of "X by Y" as "one small measure from X towards Y". It can be noted such measure ('one point') is °. So, for example, "northeast by east" means "one quarter of the gap from NE towards E".

In summary, the 32-wind compass rose comes from the eight principal winds, eight half-winds, and sixteen quarter-winds combined, with each compass point at an ° angle from the next.

Half- and quarter-points

thumb|Compass rose from American Practical Navigator, 1916

By the middle of the 18th century, the 32-point system had been further extended by using half- and quarter-points to give a total of 128 directions. These fractional points are named by appending, for example, east, east, or east to the name of one of the 32 points. Each of the 96 fractional points can be named in two ways, depending on which of the two adjoining whole points is used, for example, NE is equivalent to NbEN. Either form is easily understood, but alternative conventions as to correct usage developed in different countries and organisations. "It is the custom in the United States Navy to box from north and south toward east and west, with the exception that divisions adjacent to a cardinal or inter-cardinal point are always referred to that point." The Royal Navy used the additional "rule that quarter points were never read from a point beginning and ending with the same letter".

Compass roses very rarely named the fractional points and only showed small, unlabelled markers as a guide for helmsmen.

Maritime Use

Prior to the modern three-figure method of describing directions (using the 360° of a circle), the 32-point compass was used for directions on most ships, especially among European crews. The smallest unit of measure recognized was 'one point', 1/32 of a circle, or °. In the mariner's exercise of "boxing the compass", all thirty-two points of the compass are named in clockwise order. This exercise became more significant as navigation improved and the half- and quarter-point system increased the number of directions to include in the 'boxing'. Points remained the standard unit until switching to the three-figure degree method. These points were also used for relative measurement, so that an obstacle might be noted as 'two points off the starboard bow', meaning two points clockwise of straight ahead, ° one quarter from X towards Y), or "X al Y" (X to Y) or "X per Y" (X by Y). There are no irregularities to trip over; the closest principal wind always comes first, the more distant one second, for example: north-by-east is "Quarto di Tramontana verso Greco"; and northeast-by-north is "Quarto di Greco verso Tramontana".

The table below shows how the 32 compass points are named. Each point has an angular range of degrees where the azimuth midpoint is the horizontal angular direction (clockwise from north) of the given compass bearing; minimum is the lower (counterclockwise) angular limit of the compass point; and maximum is the upper (clockwise) angular limit of the compass point.

{| class="wikitable collapsible collapsed" style="text-align:center;"

|+ class="nowrap"| Naming of points on traditional Mediterranean compass

! rowspan="2" | No.

! rowspan="2" | Compass point

! rowspan="2" | Abbreviation

! rowspan="2" | Traditional wind point

! colspan="3" | Azimuth

! Minimum

! Midpoint

! Maximum

! 0

| align="left" |North

| N

| Tramontana

| align="right" |°

| align="right" |0°

| align="right" |°

! 1

| align="left" |North by east

| NbE

| Quarto di Tramontana verso Greco

| align="right" |°

! 2

| align="left" |North-northeast

| NNE

| Greco-Tramontana

| align="right" |°

! 3

| align="left" |Northeast by north

| NEbN

| Quarto di Greco verso Tramontana

| align="right" |°

! 4

| align="left" |Northeast

| NE

| Greco

| align="right" |°

| align="right" |45°

| align="right" |°

! 5

| align="left" |Northeast by east

| NEbE

| Quarto di Greco verso Levante

| align="right" |°

! 6

| align="left" |East-northeast

| ENE

| Greco-Levante

| align="right" |°

! 7

| align="left" |East by north

| EbN

| Quarto di Levante verso Greco

| align="right" |°

! 8

| align="left" |East

| E

| Levante

| align="right" |°

| align="right" |90°

| align="right" |°

! 9

| align="left" |East by south

| EbS

| Quarto di Levante verso Scirocco

| align="right" |°

! 10

| align="left" |East-southeast

| ESE

| Levante-Scirocco

| align="right" |°

! 11

| align="left" |Southeast by east

| SEbE

| Quarto di Scirocco verso Levante

| align="right" |°

! 12

| align="left" |Southeast

| SE

| Scirocco

| align="right" |°

| align="right" |135°

| align="right" |°

! 13

| align="left" |Southeast by south

| SEbS

| Quarto di Scirocco verso Ostro

| align="right" |°

! 14

| align="left" |South-southeast

| SSE

| Ostro-Scirocco

| align="right" |°

! 15

| align="left" |South by east

| SbE

| Quarto di Ostro verso Scirocco

| align="right" |°

! 16

| align="left" |South

| S

| Ostro

| align="right" |°

| align="right" |180°

| align="right" |°

! 17

| align="left" |South by west

| SbW

| Quarto di Ostro verso Libeccio

| align="right" |°

! 18

| align="left" |South-southwest

| SSW

| Ostro-Libeccio

| align="right" |°

! 19

| align="left" |Southwest by south

| SWbS

| Quarto di Libeccio verso Ostro

| align="right" |°

! 20

| align="left" |Southwest

| SW

| Libeccio

| align="right" |°

| align="right" |225°

| align="right" |°

! 21

| align="left" |Southwest by west

| SWbW

| Quarto di Libeccio verso Ponente

| align="right" |°

! 22

| align="left" |West-southwest

| WSW

| Ponente-Libeccio

| align="right" |°

! 23

| align="left" |West by south

| WbS

| Quarto di Ponente verso Libeccio

| align="right" |°

! 24

| align="left" |West

| W

| Ponente

| align="right" |°

| align="right" |270°

| align="right" |°

! 25

| align="left" |West by north

| WbN

| Quarto di Ponente verso Maestro

| align="right" |°

! 26

| align="left" |West-northwest

| WNW

| Maestro-Ponente

| align="right" |°

! 27

| align="left" |Northwest by west

| NWbW

| Quarto di Maestro verso Ponente

| align="right" |°

! 28

| align="left" |Northwest

| NW

| Maestro

| align="right" |°

| align="right" |315°

| align="right" |°

! 29

| align="left" |Northwest by north

| NWbN

| Quarto di Maestro verso Tramontana

| align="right" |°

! 30

| align="left" |North-northwest

| NNW

| Maestro-Tramontana

| align="right" |°

! 31

| align="left" |North by west

| NbW

| Quarto di Tramontana verso Maestro

| align="right" |°

! 32

| align="left" |North

| N

| Tramontana

| align="right" |°

| align="right" |360°

| align="right" |°

Chinese compass points

Navigation texts dating from the Yuan, Ming, and Qing dynasties in China use a 24-pointed compass with named directions. These are based on the twelve Earthly Branches, which also form the basis of the Chinese zodiac. When a single direction is specified, it may be prefaced by the character (meaning single) or .

thumb|right|260px|Ming dynasty 24-pointed compass

Headings mid-way in-between are compounds as in English. For instance, refers to the direction halfway between point and point , or °. This technique is referred to as a double-needle () compass.

{| class="wikitable"

! Point

! Ordinal Name

! Angle

| zǐ

| north

| 0° or 360°

| guǐ

| 15°

| chǒu

| 30°

| gěn

| northeast

| 45°

| yín

| 60°

| jiǎ

| 75°

| mǎo

| east

| 90°

| yǐ

| 105°

| chén

| 120°

| xùn

| southeast

| 135°

| sì

| 150°

| bǐng

| 165°

| wǔ

| south

| 180°

| dīng

| 195°

| wèi

| 210°

| kūn

| southwest

| 225°

| shēn

| 240°

| gēng

| 255°

| yǒu

| west

| 270°

| xīn

| 285°

| xū

| 300°

| qián

| northwest

| 315°

| hài

| 330°

| rén

| 345°

References

External links

Wind Rose (archived) – discusses the origins of the names for compass directions.

de:Himmelsrichtung#Systematik_der_Benennung

Designations

8-wind compass rose

Half- and quarter-points

Maritime Use

Chinese compass points

See also

References

External links