Finding accurate direction by a watch

Method for finding accurate directions by a common analogue watch.

by tonytran2015 (Melbourne, Australia).

Click here for a full, up to date ORIGINAL ARTICLE and to help fighting the stealing of readers’ traffic.

(Blog No.120).

WatchCompass_22NL

#find North, #finding North, #compass, #direction, #by Sun, #bisector, #using watch, #with watch, #tilted watch, #inclined watch, #navigation, #without compass

This method uses a common 12-hour watch with analogue face for finding directions. Unlike the traditional method of using the hour hand of a flat lying watch, my method uses a watch tilted from the vertical and gives better accuracy for both North and South hemispheres including tropical zones. When applied to the arctic and antarctic regions, the watch is tilted by more than 67 degrees and lies almost flat on the ground; it becomes the traditional method using flat lying watch.
This method use the position of the Sun, time and known latitude angle to determine directions and Sun declination (therefore estimation of current month of the year).
The method for Northern latitudes is described below.

Method for Northern latitudes.

DirectionBySun_12N

The red line is the bisector. The line CB is drawn on a card representing the half-plane to enable accurate alignment to the Sun

WatchCompass_22NL

The bisector is in the opposite direction of a corresponding 24 hr hand on a 24 hr dial

watchcompassJ

Figure: Summary of finding North by a watch. Red hand is the bisector of 0 hr direction and the hour hand; green hand is its reflection across the (6-12) axis. Axis C-BN for Northern hemisphere is parallel to red hand at equinox days and is (raised above)/(dipped below) the watch dial by 23 degrees at local summer/winter solstice. Axis C-BS for Southern hemisphere is parallel to green hand at equinox days and is (raised above)/(dipped below) the watch dial by 23 degrees at local summer/winter solstice. Green drawing marks are for Southern hemisphere and are the mirror reflection of red drawing marks.

Method for Southern latitudes.

Red hand is the bisector of 0 hr direction and the hour hand; green hand is the reflection of red hand across the (6-12) axis.

In the southern hemisphere points the green hand instead of the red hand.
No ambiguity in equatorial latitudes.
The watch is placed almost vertically in equatorial latitudes by both methods. Methods for both Northern and Southern latitudes gives exactly the same outcomes.

Extension application for both hemispheres.

Figure: Summary of finding North by a watch.

RELATED SURVIVAL BLOGS (Added in December 2016)

Caution in finding North by bisector line of a horizontal watch. Posted on October 28, 2015

Finding directions and time using the Sun and a divider., posted on May 6, 2015. <<<—This is my MOST USEFUL novel technique.

wpid-dividermwp3e2c2.jpg

find North by the Sun

Finding North direction and time using the hidden Sun via the Moon . Posted on July 6, 2015

Finding North direction and time accurately from the horn line of the Moon. Posted on August 12, 2015. This is my novel technique.

wpid-wp-1439376905855.jpeg

Finding North direction and time using the Moon surface features. Posted on July 1, 2015.

wpid-wp-1435755781395.jpeg

, posted on Circumpolar Stars Nth

Finding North and time by stars. Posted on August 28, 2015

Finding North and time with unclear sky. Posted on October 17, 2015.

wpid-bstarsn20b.jpg

, posted July 22, 2016

NorthByKnownStar

Click here for my other blogs on divider43.jpgSURVIVAL

Click here go to Divider63D400 Home Page (Navigation-Survival-How To-Money).

SUBSCRIPTION: [RSS – Posts], [RSS – Comments]

MENU: [Contents][Blog Image of Contents ][Archives ] [About]

 

Shadow stick navigation and graph of Solar paths

Shadow stick navigation and graph of Solar paths

by tonytran2015 (Melbourne, Australia).

Click here for a full, up to date ORIGINAL ARTICLE and to help fighting the stealing of readers’ traffic.

#find North, #finding North, #direction, #time, #shadow stick, #Sun shadow, #Solar declination, #graph, #Solar path,

Shadow stick navigation and graph of Solar paths.

In the 1950’s some maps have their graphs of Solar paths printed next to the compass roses. A graph of Solar paths helps the users of that map (for some certain small area) in orientating it correctly using only the direction of the Sun and the approximate time (month) in the year. It also help people visualize the direction of the Sun at each time of the year relative to a building. For some unknown reasons, graphs of Solar paths are all replaced by compass roses in modern maps. The roses take up nearly the same areas while give less information,.

A graph of Solar paths can also be used on its own with a vertical stick in the center to tell (local) time and direction. This application is suitable to day time navigation of vehicles as it relies only on the Sun and needs no battery. The application devices can be left on the vehicles as they are of very low-cost and are burglary resistant.

This posting shows how to construct and use a graph of Solar paths for your own map or for use on its own.

1. Description of the basic graph of Solar paths.

Solargraph10N

Figure: A typical graph of Solar path. This particular graph is made for 10 degrees North, for an example use in Saigon (around Tan Son Nhat International Airport).

The graph of Solar paths is a circular disc with concentric circles and radial lines bearing division marks to represent the elevation and azimuth angles of the Sun at different times of principal days.

The perimeter circle of the graph is graduated into 360 degrees to show the azimuth angle of the Sun from True North. It can also be used as a protractor for measuring angles. The concentric circles are the constant elevation circles.The radial lines are graduated 0 to 90 to show the angle from zenith to the Sun. The circle 90 degrees from the zenith represents the horizon in flat locations. The graduation can also be read from the horizon circle toward the center to show the elevation angle of the Sun.

All positions of the Sun at various time on an equinox day are plotted to make a Solar path for that day. The paths for the Sun on two solstice days are similarly plotted. The time for the each Solar position on a path is also given by time marks such as 6hr, 12hr and 18hr.

It is assumed here that the Sun attains its highest elevation at noon of local time everyday (the duration of the day is therefore slightly longer or shorter than 24hr, to discount any effect from the Equation of time).

2. Using a graph of Solar paths.

Be certain that the graph is for your current latitude! If it is printed on a map, it is for the latitude of that area.

The following steps show how to use the graph on an equinox day:

1/- Point your index to the Sun.

2/- Point your middle finger horizontally.

3/- Hold still the two fingers and measure the angle between them by placing those fingers along two radial lines of the Graph of Solar paths. Read the value of the angle. It is called the elevation angle of the Sun.

4/- Follow the Solar path for that day on the graph to its 2 points having that elevation value. The two intersection points give two times (one before and one after noon) and two positions of the Sun.

5/- Choose the one of those two points fitting your half day (either before or after noon-time).

6/- Lay the graph of Solar path horizontally. Rotate the graph until the line from the graph center to the chosen intersection point goes beneath the Sun.

7- The 0 degree azimuth line of the graph is now aligned along the direction of the true terrestrial North.

For any other day of the year, use the particular path for it. A graph supplies at least three paths: for summer solstice day (21 June for Northern Hemisphere), for equinox days (21 March and 23 September), and for winter solstice day (21 December for Northern Hemisphere). The path for any other day can be interpolated from these three.

3. Interpolation for any arbitrary day of the year.

wpid-divider10l.jpg

Figure: Solar declination for various days of the year.

The declination value for any day varies between the principal values for solstice and equinox days and its solar path varies similarly.

The rough graph here allows the estimation of how close the Solar path of any day is to its two neighbouring bounds for the equinox and solstice days.

4. Making a graph of Solar path for your latitude.

SunCelestSphere

Figure: The Celestial sphere directly above a circular disc of the same diameter.

The following steps show how to make your own graph of Solar paths for your arbitrarily chosen latitude.

1/-Draw 9 equidistant concentric circles and 12 (or 36) equally spaced radial lines as the frame for the planar polar coordinate system.

2/- Place this disc (as the frame) on a horizontal plane.

3/-Set the angle between 2 divider legs to be 90 degrees.

4/-Place the hinge of the divider exactly above the center of the disc. It should be at the center of the sphere in the figure.

5/- Hold the first leg of the divider pointing downward, inclined by latitude angle, in the 180 degree or 360 degree direction depending on your Lower Celestial pole being South or North Celestial pole. The first leg point downwards along the Celestial axis in the figure.

6/- The second leg will point at different directions to the Sun for different times of the day when the divider is rotated about the first leg. It uppermost position corresponds to mid-day.

7/- Looking downwards along the first leg of the divider gives the picture of a 24 hour clock with the second leg being the hour hand. The clock dial is clockwise when you are in Northern hemisphere and anticlockwise when Southern.

8a/- Looking at the second leg from the top of the disc gives azimuth angle of the Sun.

8b/- Looking at the second leg from its side gives elevation angle of the Sun.

9/- Record on the polar graph on the disc the direction of the second leg for 6hr, 12hr and 18hr.

10/- Join the curve by a smooth curve. (Additional points may be added for a more precise curve).

11/- The curve is the Solar path for equinox days.

12/- Set the angle between the divider legs to 90+23.5 degrees and repeat steps 4 to 10 to draw Solar path for summer solstice day.

13/- Set the angle between the divider legs to 90-23.5 degrees and repeat steps 4 to 10 to draw Solar path for winter solstice day.

The graph of Solar paths is now COMPLETE. It is usable with only 3 paths for equinox and solstice days. Paths for other days can be interpolated from them.

Manually drawn graphs are accurate enough for normal usage. If all steps are simulated with your computer, the graph will be very accurate.

If you live near to 20 degrees N latitude (20 degrees is only an example value) and need a graph for your personal use but don’t want to spend time drawing it, you can do a Google search for “graph solar path 20 degrees”. The search results will give many ready made graphs and you can select one of them for your own use.

5. Application 1: Shadow stick navigation for vehicles.

ShadowStick

Picture of Application 1: Shadow stick navigation for vehicles.

You can print your graph on a disc for use in your vehicle. You can use only one single disc if the vehicle does not travel more than 5 degrees = 300 nautical miles = 555km in latitude from your base.

Lay the rotatable disc horizontally with a vertical stick at its center. When the shadow of the stick is on the opposite side of the chosen point on the graph, the line of 0 degree points exactly at True North. This method of Solar navigation only needs the graph and a vertical stick and is immune to vehicle shocks and stray magnetism.

This method needs the above device and is less general than my other methods given in references [1, 2, 3] but may be easier for users to comprehend.

6. Application 2: As a North direction marker

DirectionMarker

Picture of Application 2: As a North direction marker

Figure: Map of an old citadel overlaid on a modern satellite based map. The graph of Solar paths is given on bottom left corner instead of the compass rose.

The illustration is the map of an old citadel overlaid on a modern satellite based map. The graph of Solar paths is given on bottom left corner instead of the compass rose. The graph of Solar paths gives more useful information than a compass rose occupying same area.

Notes on my composite map: The modern map data are used under Open License from Open Street Map, the data are owned by Open Street Map Contributors. The old area has adjusted and selected data from a 150 year old map with expired Copyright.

7. Additional observations.

The graph of step 1 shows that the Sun can travel on the other side of your zenith when you are in a tropical zone. This explains why the bisector method using a horizontal watch may give you an error of 180 degrees around summer solstice (see reference [2]).

The graph shows that the terrestrial direction (azimuth) angle of the Sun varies quickly with time when the Sun is close to the zenith point. This quick change in direction may be main the reason for the ancient custom of cross-country travelers to take their rest when the Sun is near to their zenith.

You can also use a graph for your EXACT latitude to calculate if and for how long a proposed neighbouring tall building may over-shadow your house. Architects have been using graph of Solar paths and physical sunlight simulator on their scale models even before 1914.

References.

[1]. tonytran2015, Finding directions and time using the Sun and a divider, survivaltricks.wordpress.com, https://survivaltricks.wordpress.com/2015/05/06/finding-directions-and-time-using-the-sun-and-a-dividing-compass/, posted on May 6, 2015.

find North by the Sun

[2]. tonytran2015, Finding accurate directions using a watch, survivaltricks.wordpress.com, https://survivaltricks.wordpress.com/2015/05/19/finding-accurate-directions-using-a-watch/, posted May 19, 2015

[3]. tonytran2015, Caution in finding North by bisector line of a horizontal watch, survivaltricks.wordpress.com, https://survivaltricks.wordpress.com/2015/10/28/caution-in-finding-north-by-bisector-line-of-a-horizontal-watch/, Posted on October 28, 2015.

RELATED SURVIVAL blogs
, posted on 2018 July 10

Find North By Fingers

Finding North with a lensatic compass, posted on August 21, 2017

Compass-Magnetic

Selecting and using magnetic compasses, posted on July 9, 2016

JapLensatic

Finding North direction and time using the hidden Sun via the Moon . Posted on July 6, 2015

image

Finding North direction and time using the Moon surface features. Posted on July 1, 2015.

image

, posted on

Finding North and time by stars. Posted on August 28, 2015 .

Sky map Northern 3/4 sphere

Sky map Southern 3/4 sphere

Navigating with an AM MW radio receiver, posted January 17, 2017, The Scorpius constellation, posted January 8, 2017, The Orion constellation., posted December 26, 2016, Rice as emergency food., Using GPS in off-grid situations, Slide Sky-Disks with grid masks showing azimuths and altitudes, Slide Sky-Map for displaying tropical stars.

Click here for my other blogs on divider43.jpgSURVIVAL

divider43.jpg

polymeraust100dollars

Click here go to Divider63D400 Home Page (Navigation-Survival-How To-Money).

SUBSCRIPTION: [RSS – Posts], [RSS – Comments]

MENU: [Contents][Blog Image of Contents ][Archives ] [About]

Finding accurate directions by a watch .

Method for finding accurate directions by a watch in any latitude.

by tonytran2015 (Melbourne, Australia).

Click here for a full, up to date ORIGINAL ARTICLE and to help fighting the stealing of readers’ traffic.

#find North, #finding North, #compass, #direction, #bisector, #using watch, #with watch, #tilted watch, #inclined watch, #navigation, #without compass

This method uses a watch with analogue face for finding directions. Unlike the traditional method of using the hour hand of a flat lying 24-hour watch, my method uses a 24-hour watch tilted from the vertical and gives better accuracy for both North and South hemispheres including tropical zones. When applied to the arctic and antarctic regions, the watch is tilted by more than 67 degrees and lies almost flat on the ground; it becomes the traditional method using flat lying 24-hour watch.

The method assumes an analogue 24-hour watch is in use. For any analogue 12-hour watch, the bisector between its midnight marking and its 12-hour hand can serve as an imaginary 24-hour hand. From the latitude of the place, the position of the Sun in the sky and the local time shown on the watch, the method gives out the Cardinal directions and declination of the Sun (therefore an estimation of the date and month in the year.

The method for Northern latitudes is described first and is followed by the method for Southern latitudes.

Method for Northern latitudes:

WatchCompass_22NL

A 24-hour watch shown only with hour hand

1/- Hold the watch so that its AXIS rises above the horizontal plane by an angle equal to the latitude of the region. That is its face points to somewhere in the sky and its back is angled downwards into the ground.

2N/- Determine the half-plane limited by the axis of the watch and the backward pointing direction of the 24-hr pointer (the hour hand of the 24hr watch). This half-plane will contain the Sun if this watch displays the local time and the face of the watch and its axis points to the North Star.

3N/-Determine ON THIS SEMI-PLANE a half-line CB from the centre C of its dial, forming with the watch axis an angle equal to the angle between the direction to the Sun and the Northern Star. The half-line CB starts from the centre of the dial and is nearly in the opposite direction of the 24-hour hand (pointer). It rises above the dial toward the glass and points through the glass of the watch during summer time and dives below the dial into the movement compartment of the watch and points through the movement of the watch during winter time. This half-line always points to the Sun if this 24-hr watch displays the local time and the face of the watch and its axis point to the North Star.

4N/- Hold the clock in such composure and rotate your whole body around your vertical axis by your feet until the above half-line CB points towards the Sun (Therefore the Sun lies in the half-plane limited by the watch axis and the backward pointing direction of the 24-hour pointer). At that position, the watch face and its AXIS are POINTING to the North Star.

5/- The projection of the Celestial axis onto the horizontal ground is then the terrestrial Northern-South direction.

The method for determining the North-South direction in the Southern hemisphere is different but is very similar to this method for the North. Paragraphs 2N, 3N and 4N are appropriately replaced by 2S, 3S and 4S for Southern latitudes as in the following.

Method for Southern latitudes:

2S/- The UP-DOWN REFLECTION OF THE HOUR HAND of a 24-hour watch is its imaginary hour hand going anti-clockwise, pointing downwards at midnight and upwards at midday. It is the reflection of the hour hand of a vertically hung 24-hour watch through any water surface below it.

Determine the half-plane limited by the axis of the watch and the up-down reflection of the hour hand. This half-plane will contain the Sun if this 24-hr watch displays the local time and the face of the watch and its axis point to the Southern Celestial pole, while the back of the watch points through the ground to the North Star.

3S/-Determine ON THIS SEMI-PLANE a half-line CB from the centre C of its dial, forming with the watch axis an angle equal to the angle between the direction to the Sun and the Southern Celestial pole. The half-line CB starts from the centre of the dial and is nearly in the direction of the up-down reflection of the 24-hour hand. It rises above the dial toward the glass and points through the glass of the watch during Southern Hemisphere’s summer and dives below the dial into the movement compartment of the watch and points through the movement of the watch during the Southern Hemisphere’s winter. This half-line always points to the Sun if this 24-hr watch displays the local time and the face of the watch and its axis point to the Southern Celestial pole.

4S/- Hold the clock in such composure and rotate your whole body around your vertical axis by your feet until the above half-line CB points towards the Sun (Therefore the Sun lies in the half-plane limited by the watch axis and the up-down reflection of the 24-hour pointer). At that position, the watch face and its AXIS are POINTING to the Southern Celestial pole while the back of the watch points through the ground to the North Star.

No ambiguity in equatorial latitudes.

The watch is placed almost vertically in equatorial latitudes by both methods. Methods for both Northern and Southern latitudes give exactly the same outcomes.

Adaptation for use with any common 12 hr watch.

The method is easily modified for application to any common 12 hr watch. In the following figure, the red hand (the bisector of the 0hr direction and the hour hand of a common 12hr watch ) is in the opposite direction of the hour hand of a 24hr watch.

WatchCompassG

Figure: Summary of finding North by a watch. Red hand is the bisector of 0 hr direction and the hour hand; green hand is its reflection across the (6-12) axis. Axis C-BN for Northern hemisphere is parallel to red hand at equinox days and is (raised above)/(dipped below) the watch dial by 23 degrees at local summer/winter solstice. Axis C-BS for Southern hemisphere is parallel to green hand at equinox days and is (raised above)/(dipped below) the watch dial by 23 degrees at local summer/winter solstice. Green drawing marks are for Southern hemisphere and are the mirror reflection of red drawing marks.

Figure: Summary of finding North by a watch.

Actual field test

The author has tested these methods and found them to be applicable, easy and accurate to within 30 degrees for latitudes from 0 to 40 degrees.

Explanation notes:

N1/- The word “watch” here applies to any watch or clock.

N2/- When a watch or a clock dial is hung on a vertical wall, its midnight marking is at the highest position. If the hour hand of a watch completes one revolution in 24 hours the watch is called a 24-hour watch; if it completes in 12 hour the watch is called a 12-hour watch. Most watches and domestic clocks are 12-hour ones. The bisector of the midnight marking and the hour hand of any 12-hour watch complete one revolution in 24 hour. It moves like an imaginary 24-hour hand on that watch.

N3/-The axis of the watch is the oriented line (Note that it is more than “the oriented half-line”.) going through the centre of the watch at right angle to its dial disc and is parallel to the rotation axes of both the minute pointer (or “minute hand”) and the hour pointer (or “hour hand”). The direction chosen on the line is from the back to the front face of the watch.

N4/- A watch display local time when it shows 12 o’clock when the Sun is highest in the sky.

N5/- The angle between the North Star and the Sun varies like a sine wave with amplitude of 23.5 degrees; it should be 90 degree during Spring and Autumn equinoxes and 90-23.5 degree at Northern Summer solstice (21st June) and 90+23.5 degree at Northern Winter solstice (21st of December).

(Added after December 2016) RELATED SURVIVAL blogs

Finding accurate directions using a watch, posted on May 19, 2015


, posted on 2018 July 10

Find North By Fingers

Finding directions and time using the Sun and a divider., posted on May 6, 2015. <<<—This is my MOST USEFUL novel technique.

wpid-dividermwp3e2c2.jpg

find North by the Sun

Finding North direction and time using the hidden Sun via the Moon . Posted on July 6, 2015

image

Finding North direction and time accurately from the horn line of the Moon. Posted on August 12, 2015. This is my novel technique.

image

Finding North direction and time using the Moon surface features. Posted on July 1, 2015.

image

, posted on

Finding North and time by stars. Posted on August 28, 2015

Sky map Northern 3/4 sphere

Sky map Southern 3/4 sphere

Finding North and time with unclear sky. Posted on October 17, 2015.

image

image

, posted July 22, 2016

DirectionTimeByStars

Click here for my other blogs on divider43.jpgSURVIVAL

divider43.jpg

polymeraust100dollars

Click here go to Divider63D400 Home Page (Navigation-Survival-How To-Money).

SUBSCRIPTION: [RSS – Posts], [RSS – Comments]

MENU: [Contents][Blog Image of Contents ][Archives ] [About]

Using polarized light to locate the Sun when it is hidden from view.

Using polarized light to locate the Sun when it is hidden from view.

by tonytran2015 (Melbourne, Australia).

Click here for a full, up to date ORIGINAL ARTICLE and to help fighting the stealing of readers’ traffic.

#find, #finding, #Sun, #North, #navigation, #survival, #find the Sun, #polarize, #light, #ray, #Sunlight, #Sunray, #sunglasses, #compass, #direction, #time

Anti-glare polarizing sunglasses reduce horizontally polarized rays. They can also be useful in locating the Sun even when it is hidden from view by clouds or by the horizon. Locating the Sun enables determination of compass direction and time for navigation without any compass.

1. Basic information

Two walkie-talkies are in the best condition for communication when their two antennas are parallel and at right angle to their line of view. The electric waves traveling between them have their electric field parallel to the emitting antenna and the varying electric field is at right angle to the line of transmission. The electromagnetic waves is said to be polarized in the direction of the emitting antenna.

Light is just electromagnetic waves at much higher frequencies than our familiar radio waves. Light can be polarized too. Light rays from incandescent sources are randomly polarized like radio waves coming from a walkie-talkie which is randomly orientated before each transmission. On the average we don’t see any polarization from a source with randomly changing orientation. However after a partial reflection (accompanied by a partial transmission) at an interface between two transmission media, the reflected and the transmitted rays from any non-polarized ray becomes partially polarized.

Polarizing sunglasses can favour light polarized in one direction and discriminate against light polarized in the other direction. With the same pair of sunglasses we can see two different colours and brightnesses depending on the orientation of the glasses when viewing the same source. This is illustrated in the following figure.

Be certain that your polarizing glasses really reduces sunlight reflecting off horizontal road surfaces before trying subsequent instructions here; each of the glasses must be individually tested and its direction of polarization verified.

2. Different colours and degrees of brightness seen from the same source of light through polarizing sunglasses

skylight through polarizing sunglasses

The cross with two different colours on the source denotes the two different colours seen through two orientations of the same sunglasses.

3. Seeing the polarized lights of the sky

polarization of scattered blue sunlight

The polarization of scattered blue sunlight in the sky

Blue light from the sky is the result of Rayleigh scattering of photons from sunlight by molecules in the sky. This scattered light is highly polarized as seen in the following practice:

Search for a large clear patch of sky with no cloud. Look through the polarizing glasses. Rotate the glasses about the axis of view to see the sky lightens and darkens alternatingly with the angle of rotation. The darkening is most profound when the Sun is at right angle to the line of view.

4. Locating the hidden Sun.

Locating the hidden Sun using polarized light

Locating the hidden Sun from two patches of clear sky.

1/- Search for a large clear patch of sky with no cloud. Rotate the glasses about the axis of view until the clear sky becomes most darkened. The Sun is then on the great circle perpendicular to the line joining the left and right spectacles (Being the intersection of the Celestial sphere and the symmetry plane of the sunglasses). The darkening is most profound when the Sun is at right angle to the line of view.

2/- Repeat with a second clear patch of the sky. Two large clear patches of the sky can give out the position of the hidden Sun. It is at the intersection of the two so obtained great circles in the sky.

3/- The position of the Sun below the sky-line can also be found using polarized light-rays from the clear sky above its (underground) line of view. If the illustration picture of this section is turned up side down with a horizon line added above its Sun it will illustrate how to find the Sun when it is below the horizon (The polarization is most profound on the clear sky at 90 degree to the (underground) line of view of the Sun.).

Reference [2] gives some interesting history of the early applications of polarization of light. Currently there have even been hypotheses that the Vikings had used polarized light to locate the Sun since antiquity with pieces of birefringent calcite crystals [1].

References.

[1]. Cahal Milmo, Not just the stuff of legend: Famed Viking ‘sunstone’ did exist, believe scientists,
The Independent, http://www.independent.co.uk/news/science/archaeology/not-just-the-stuff-of-legend-famed-viking-sunstone-did-exist-believe-scientists-8521522.html, 06 March 2013, 21 May 2015.

[2]. Unknown Authors, Polarization (waves), Wikipedia, http://en.wikipedia.org/wiki/Polarization_%28wave… 26 May 2015

[3]. Unknown Authors, Following the Light of the Sky, polarization.net, https://www.polarization.com/compass/compass.html… Accessed 16 May 2015 05:40:14 GMT.

[4]. tonytran2015, Finding North direction and time using the Sun and a divider, http://www.survivaltricks.wordpress.com/, 06 May 2015.

(The following is added after 20 May 2017)

[5]. Israel Ramirez, https://www.quora.com/What-can-animals-that-can-see-the-polarization-of-light-see-that-other-animals-cannot, 28 Nov 2016.

[6]. tonytran2015, Finding North in the polar zones using equatorial stars and the Sun, https://survivaltricks.wordpress.com/2017/05/24/finding-north-in-the-polar-zones-using-equatorial-stars-and-the-sun/, posted May 24, 2017,

RELATED SURVIVAL blogs

Finding North in the polar zones using equatorial stars and the Sun, posted May 24, 2017,

Find North with Orion Equatorial stars

Finding directions and time using the Sun and a divider., posted on May 6, 2015.

wpid-dividermwp3e2c2.jpg

find North by the Sun

Finding-time-to-sunset-with-bare-hands/, posted November 11, 2015,

Navigating with an AM MW radio receiver, posted January 17, 2017, The Scorpius constellation, posted January 8, 2017, The Orion constellation., posted December 26, 2016, Rice as emergency food., Using GPS in off-grid situations, Slide Sky-Disks with grid masks showing azimuths and altitudes, Slide Sky-Map for displaying tropical stars.

Click here for my other blogs on divider43.jpgSURVIVAL

divider43.jpg

polymeraust100dollars

Click here go to Divider63D400 Home Page (Navigation-Survival-How To-Money).

SUBSCRIPTION: [RSS – Posts], [RSS – Comments]

MENU: [Contents][Blog Image of Contents ][Archives ] [About]