Gnomon--History for Determining North

In a book on prehistoric astronomy, the author describes the use of a gnomon to
determine E-W from the sun. One drives a stick, the gnomon, into the ground and marks
the tip of the shadow of the sun. Then sometime later this is done again. A line
drawn through the two points is E-W. So my questions are 1. how accurate is this
method and 2. who was the first to discover it, and 3. when was it discovered it?
--
Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA)
(121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
Obz Site: 39° 15' 7" N, 121° 2' 32" W
(Formerly Homo habilis, erectus, heidelbergensis and now sapiens)

Sturgeons (Endangered) can live 100 years and weigh 2500 pounds.

Web Page: home.earthlink.net/~mtnviews

In a book on prehistoric astronomy, the author describes the use of a gnomon
to determine E-W from the sun.
...my questions a
1. how accurate is this method ?
2. who was the first to discover ?
3. when was it discovered ?

I don't know about 'prehistoric' astronomy, but ancient astronomy records
generally credit Anaximander with the first use of the gnomon (shadow-chaser)
in the 5th century B.C.
It was first used only to predict midday, and the coming of solstices
and equinoxes.
Later, a 'dial' was placed below the gnomon and divided into
'hour' lines from sunrise to sunset.
http://www.perseus.tufts.edu/GreekSc...ris/TIME2.html

SSX

I am not sure about that, but I do know that the Apollo astronauts used
a gnomon on the moon strictly as a scale for documenting moon rock
samples. This gnomon also had a color chart for film calibration.
I use a variant of this to take architectural photographs in the sign
business, using a three foot tall marked stick as a known scale.

Matthew Ota

W. Watson wrote:

In a book on prehistoric astronomy, the author describes the use of a
gnomon to determine E-W from the sun. One drives a stick, the gnomon,
into the ground and marks the tip of the shadow of the sun. Then
sometime later this is done again. A line drawn through the two points
is E-W. So my questions are 1. how accurate is this method and 2. who
was the first to discover it, and 3. when was it discovered it?

SaberScorpX wrote:

In a book on prehistoric astronomy, the author describes the use of a gnomon

to determine E-W from the sun.

...my questions a
1. how accurate is this method ?
2. who was the first to discover ?
3. when was it discovered ?


I don't know about 'prehistoric' astronomy, but ancient astronomy records
generally credit Anaximander with the first use of the gnomon (shadow-chaser)
in the 5th century B.C.
It was first used only to predict midday, and the coming of solstices
and equinoxes.
Later, a 'dial' was placed below the gnomon and divided into
'hour' lines from sunrise to sunset.
http://www.perseus.tufts.edu/GreekSc...ris/TIME2.html

SSX

The book in question is "Prehistoric Astronomy in the Southwest" by J. Mckim Malville
and Claudia Putnam.


--
Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA)
(121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
Obz Site: 39° 15' 7" N, 121° 2' 32" W
(Formerly Homo habilis, erectus, heidelbergensis and now sapiens)

"The truth is a precious commodity. That's why it is sparsely used."
-- Mark Twain

Web Page: home.earthlink.net/~mtnviews

The book in question is "Prehistoric Astronomy in the Southwest" by
J. Mckim Malville and Claudia Putnam.

I believe you. Found a review he
http://pages.prodigy.net/pam.orman/j..._malville.html

'Prehistoric astronomy' just makes me think of dinosaurs with dobs

SSX