To add just a bit of precision (and fun) to this:
1. Draw a series of concentric circles using your shadow stick as the center. Note where the shadow of the stick "touches" each circle on its morning and afternoon side. [Only one is needed, but clouds may not cooperate, so prepare a few.] Now connect the two points where the sun's shadow touched the same circle. Find the perpendicular bisector of this line and draw a line from the point ( the perpendicular bisector that is) to the stick. THIS is a true north south line.
2. The north star approach is interesting for many reasons. Polaris
is not exactly at true north. While finding the star from the Big Dipper,
as any Boy Scout will attest, is adequate, it is interesting to note that
Polaris circles the True North Pole in a counter clockwise direction at
a distance of about 48' of arc. Using the fifth star in the Constellation
Cassiopeia and the Big Dipper, you can get a slightly better estimate.
A line through said star, polaris as shown will go through the North Pole.
:
Now how to measure 48' ? This is a bit trickier and requires a
bit of preparation and a ruler.
a.) Hold your arm at full length in front of you and site on a ruler.
If the ruler is 57 cm from your eye ( have a friend measure this) ,then
one cm. of the ruler will subtend an angle of 1 º ( Actually
since one radian is approx. 57º of arc, any measure will do; set up
sticks [if you must] 57 units from your site (ie, eyeball) and view
the angle of 1 similar unit; this angle will be 1 º) Actually my eye
is 55 cm from my extended arm ( an average of many many measures over the
years) ; one cm on my ruler is therefor 1.04º (You can define
this angle for your extended fist, two fingers etc and really baffle your
friends; its great fun and can be useful in emergencies.)
By the way, my backpack has a card in it I made up with the sun's Declination for 1st and 15th of each month, the EoT for each, and Declinations and Hour Angles of some favorite stars. You can spot an approximation of the First Point of Aries from Pagasus. You probably would have an accurate wrist watch ( I keep mine to +/- 3sec/month using WWV) or at best can define LAN from the sun and est. from EoT on the card. Now with your calibrated arm/finger/fist/ruler you can do quite a lot.
I go out with my grandkids and practice getting lost on field trips. It is actually fun. Of course knowing you can Phone Home anytime helps. ( I trust Slawomir will have much to add)
Happy Dialing
DAVE
33º 30' N 118º W
Michael Koblic wrote:
I have just watched some videos on wilderness survival. An otherwiseContent-Type: image/jpeg Content-ID: <[EMAIL PROTECTED]> Content-Disposition: inline; filename="C:\WINDOWS\TEMP\nsmailF2.jpeg" Attachment converted: MAC Hard Disk:C-\WINDOWS\TEMP\nsmailF2.jpeg (JPEG/JVWR) (00002CCA) Content-Type: image/jpeg Content-ID: <[EMAIL PROTECTED]> Content-Disposition: inline; filename="C:\WINDOWS\TEMP\nsmail9K.jpeg" Attachment converted: MAC Hard Disk:C-\WINDOWS\TEMP\nsmail9K.jpeg (JPEG/JVWR) (00002CCB)
excellent series showed amongst other things how to determine northerly
direction by two methods:1) By using a shadow stick (pegging out the successive peaks of the shadow
thrown by a vertical stick, the line of pegs then being east-west line, the
north-south line perpendicular to it)2) By polar star
