Principle of the Lat/Long system
 

This is the broadest possible overview for those who are unfamiliar with how the motions of the Earth fit in with human timekeeping and although it is an injustice to those people who created the system we use today, the overview is much better than none at all. There is no stopping to differentiate between the original geocentric astronomers and their observations from the later heliocentric astronomers who worked off the idea that the Earth moves between Venus and Mars around the Sun so readers today don't concern themselves with the level of knowledge of any given era as this will be taken for granted in order to move the story along.

As the Earth moves through space in its circuit around the Sun,certain stars lying on or near the same plane as the Earth's orbital motion are temporarily lost behind the Sun's glare. The older astronomers marked the passage as the Sun through the constellations (hence birth signs) but for purposes of this story it is better to consider the apparent motion of the stars behind the Sun due to the orbital motion of the Earth -

https://www.youtube.com/watch?v=eeQwYrfmvoQ

The anchor for the Lat/Long system originally was based on the appearance of one particular star as the orbital motion of the Earth placed the star just far enough to one side of the Sun one morning, That star was the brightest one in the celestial arena known as Sirius and can be seen on the bottom left of the image -

https://www.youtube.com/watch?v=eeQwYrfmvoQ

".. on account of the procession of the rising of Sirius by one day in the course of 4 years,.. therefore it shall be, that the year of 360 days and the 5 days added to their end, so one day shall be from this day after every 4 years added to the 5 epagomenae before the new year" Canopus Decree 238 BC

Unbeknownst to themselves, what the Egyptians were actually doing was defining the Earth's orbital position around the Sun using the seasonal appearance of a star as a gauge and the number of rotations that fit inside an orbital circuit, in this case 1461 rotations for 4 orbital circuits which breaks down into 365 1/4 rotations to one orbital circuit.

This is the founding principle where one 24 hour day keeps in step with one rotation of the Earth and the basis of the Lat/Long system along with the reason why the extra day and rotation is introduced in order to keep the Earth's position in space fixed by the number of rotations,at least to the nearest rotation.

The next step is the process which equates the 'average' 24 hour day with 'constant' rotation insofar as the average 24 hour day substitutes for constant rotation through 360 degrees in that period.

Principle of the Lat/Long system
 

Apologies,the correct image is reproduced.


On Saturday, January 3, 2015 8:14:28 AM UTC-8, Gerald Kelleher wrote:
This is the broadest possible overview for those who are unfamiliar with how the motions of the Earth fit in with human timekeeping and although it is an injustice to those people who created the system we use today, the overview is much better than none at all. There is no stopping to differentiate between the original geocentric astronomers and their observations from the later heliocentric astronomers who worked off the idea that the Earth moves between Venus and Mars around the Sun so readers today don't concern themselves with the level of knowledge of any given era as this will be taken for granted in order to move the story along.

As the Earth moves through space in its circuit around the Sun,certain stars lying on or near the same plane as the Earth's orbital motion are temporarily lost behind the Sun's glare. The older astronomers marked the passage as the Sun through the constellations (hence birth signs) but for purposes of this story it is better to consider the apparent motion of the stars behind the Sun due to the orbital motion of the Earth -

https://www.youtube.com/watch?v=eeQwYrfmvoQ

The anchor for the Lat/Long system originally was based on the appearance of one particular star as the orbital motion of the Earth placed the star just far enough to one side of the Sun one morning, That star was the brightest one in the celestial arena known as Sirius and can be seen on the bottom left of the image -


http://www.gautschy.ch/~rita/archast...liacsirius.JPG




".. on account of the procession of the rising of Sirius by one day in the course of 4 years,.. therefore it shall be, that the year of 360 days and the 5 days added to their end, so one day shall be from this day after every 4 years added to the 5 epagomenae before the new year" Canopus Decree 238 BC

Principle of the Lat/Long system
 

wrote:
On Sat, 3 Jan 2015 08:14:26 -0800 (PST),
wrote:

This is the broadest possible overview for those who are unfamiliar with
how the motions of the Earth fit in with human timekeeping and although
it is an injustice to those people who created the system we use today,
the overview is much better than none at all. There is no stopping to
differentiate between the original geocentric astronomers and their
observations from the later heliocentric astronomers who worked off the
idea that the Earth moves between Venus and Mars around the Sun so
readers today don't concern themselves with the level of knowledge of
any given era as this will be taken for granted in order to move the story along.

As the Earth moves through space in its circuit around the Sun,certain
stars lying on or near the same plane as the Earth's orbital motion are
temporarily lost behind the Sun's glare. The older astronomers marked
the passage as the Sun through the constellations (hence birth signs)
but for purposes of this story it is better to consider the apparent
motion of the stars behind the Sun due to the orbital motion of the Earth -

https://www.youtube.com/watch?v=eeQwYrfmvoQ

The anchor for the Lat/Long system originally was based on the
appearance of one particular star as the orbital motion of the Earth
placed the star just far enough to one side of the Sun one morning, That
star was the brightest one in the celestial arena known as Sirius and
can be seen on the bottom left of the image -

https://www.youtube.com/watch?v=eeQwYrfmvoQ

".. on account of the procession of the rising of Sirius by one day in
the course of 4 years,.. therefore it shall be, that the year of 360
days and the 5 days added to their end, so one day shall be from this
day after every 4 years added to the 5 epagomenae before the new year"
Canopus Decree 238 BC

Unbeknownst to themselves, what the Egyptians were actually doing was
defining the Earth's orbital position around the Sun using the seasonal
appearance of a star as a gauge and the number of rotations that fit
inside an orbital circuit, in this case 1461 rotations for 4 orbital
circuits which breaks down into 365 1/4 rotations to one orbital circuit.

This is the founding principle where one 24 hour day keeps in step with
one rotation of the Earth and the basis of the Lat/Long system along
with the reason why the extra day and rotation is introduced in order to
keep the Earth's position in space fixed by the number of rotations,at
least to the nearest rotation.

The next step is the process which equates the 'average' 24 hour day
with 'constant' rotation insofar as the average 24 hour day substitutes
for constant rotation through 360 degrees in that period.






I am reacquainting myself with celestial mechanics as I am playing
with my new sextant.

I inherited an airplane sextant and only tried to play with it once. Has a
disk that a pencil lead marks to get an average of the horizon in a moving
airplane. Is missing the degree wheel I think.

Principle of the Lat/Long system
 

Having established the original method by which humans came to understand how the appearance of a star defined the Earth's orbital position around the Sun and the number of times it turns within the confines of that orbital circuit using an extra day and rotation over a 4 year period and 4 orbital circuits, the use of the average day and modern timekeeping comes into view. No better person than the great John Harrison to explain the principles -

"The application of a Timekeeper to this discovery is founded upon the
following principles: the earth's surface is divided into 360 equal parts (by imaginary lines drawn from North to South) which are called Degrees of Longitude; and its daily revolution Eastward round its own axis is performed in 24 hours; consequently in that period, each of those imaginary lines or degrees, becomes successively opposite to the Sun (which makes the noon or precise middle of the day at each of those degrees;) and it must follow, that from the time any one of those lines passes the Sun, till the next passes, must be just four minutes, for 24 hours being divided by 360 will give that quantity; so that for every degree of Longitude we sail Westward, it will be noon with us four minutes the later, and for every degree Eastward four minutes the sooner, and so on in proportion for any greater or less quantity. Now, the exact time of the day at the place where we are, can be ascertained by well known and easy observations of the Sun if visible for a few minutes at any time from his being ten degrees high until within an hour of noon, or from an hour after noon until he is only 10 degrees high in the afternoon; if therefore, at any time when such observation is made, a Timekeeper tells us at the same moment what o'clock it is at the place we sailed from, our Longitude is
clearly discovered." John Harrison

So here we have the 24 hour day linked to the passage of the Sun across the meridian each day where one rotation and one day always keep in step and especially February 29th which represents the older astronomical achievement that pins the Earth to its orbital position.

The next explanation is intricate but if readers can follow the principles so far that anchor the 24 hour day to rotation there is little that can go wrong understanding the next step which ties the Lat/Long system to the 24 hour AM/PM system.

Principle of the Lat/Long system
 

On Sun, 4 Jan 2015 07:06:49 -0800 (PST), Gerald Kelleher
wrote:

Having established the original method by which humans came to understand how the appearance of a star defined the Earth's orbital position around the Sun and the number of times it turns within the confines of that orbital circuit using an extra day and rotation over a 4 year period and 4 orbital circuits, the use of the average day and modern timekeeping comes into view. No better person than the great John Harrison to explain the principles -

"The application of a Timekeeper to this discovery is founded upon the
following principles: the earth's surface is divided into 360 equal parts (by imaginary lines drawn from North to South) which are called Degrees of Longitude; and its daily revolution Eastward round its own axis is performed in 24 hours; consequently in that period, each of those imaginary lines or degrees, becomes successively opposite to the Sun (which makes the noon or precise middle of the day at each of those degrees;) and it must follow, that from the time any one of those lines passes the Sun, till the next passes, must be just four minutes, for 24 hours being divided by 360 will give that quantity; so that for every degree of Longitude we sail Westward, it will be noon with us four minutes the later, and for every degree Eastward four minutes the sooner, and so on in proportion for any greater or less quantity. Now, the exact time of the day at the place where we are, can be ascertained by well known and easy observations of the Sun if visible for a few minutes at any time
from his being ten degrees high until within an hour of noon, or from an hour after noon until he is only 10 degrees high in the afternoon; if therefore, at any time when such observation is made, a Timekeeper tells us at the same moment what o'clock it is at the place we sailed from, our Longitude is
clearly discovered." John Harrison

So here we have the 24 hour day linked to the passage of the Sun across the meridian each day where one rotation and one day always keep in step and especially February 29th which represents the older astronomical achievement that pins the Earth to its orbital position.

The next explanation is intricate but if readers can follow the principles so far that anchor the 24 hour day to rotation there is little that can go wrong understanding the next step which ties the Lat/Long system to the 24 hour AM/PM system.

===

Good grief, we've been dealing with imaginary boats on this group for
years. Now we have to deal with imaginary lines also? I've seen
those lines and they are just as real as Harry's boats.

Principle of the Lat/Long system
 

On Sunday, January 4, 2015 8:35:33 AM UTC-8, Wayne. B wrote:
On Sun, 4 Jan 2015 07:06:49 -0800 (PST), Gerald Kelleher
wrote:

Having established the original method by which humans came to understand how the appearance of a star defined the Earth's orbital position around the Sun and the number of times it turns within the confines of that orbital circuit using an extra day and rotation over a 4 year period and 4 orbital circuits, the use of the average day and modern timekeeping comes into view. No better person than the great John Harrison to explain the principles -

"The application of a Timekeeper to this discovery is founded upon the
following principles: the earth's surface is divided into 360 equal parts (by imaginary lines drawn from North to South) which are called Degrees of Longitude; and its daily revolution Eastward round its own axis is performed in 24 hours; consequently in that period, each of those imaginary lines or degrees, becomes successively opposite to the Sun (which makes the noon or precise middle of the day at each of those degrees;) and it must follow, that from the time any one of those lines passes the Sun, till the next passes, must be just four minutes, for 24 hours being divided by 360 will give that quantity; so that for every degree of Longitude we sail Westward, it will be noon with us four minutes the later, and for every degree Eastward four minutes the sooner, and so on in proportion for any greater or less quantity. Now, the exact time of the day at the place where we are, can be ascertained by well known and easy observations of the Sun if visible for a few minutes at any time
from his being ten degrees high until within an hour of noon, or from an hour after noon until he is only 10 degrees high in the afternoon; if therefore, at any time when such observation is made, a Timekeeper tells us at the same moment what o'clock it is at the place we sailed from, our Longitude is
clearly discovered." John Harrison

So here we have the 24 hour day linked to the passage of the Sun across the meridian each day where one rotation and one day always keep in step and especially February 29th which represents the older astronomical achievement that pins the Earth to its orbital position.

The next explanation is intricate but if readers can follow the principles so far that anchor the 24 hour day to rotation there is little that can go wrong understanding the next step which ties the Lat/Long system to the 24 hour AM/PM system.

===

Good grief, we've been dealing with imaginary boats on this group for
years. Now we have to deal with imaginary lines also? I've seen
those lines and they are just as real as Harry's boats.

What you may take for granted in a joking way would have been a serious issue at one stage in history -

http://en.wikipedia.org/wiki/Scilly_...saster_of_1707

The connection between the Lat/Long system along with timekeeping and how it meshes with planetary daily and orbital dynamics has never been explained properly hence this thread.

Anyone with the confidence of a skipper would have no problem so far with the explanation but we are sailing into stormy conceptual waters soon before returning to calmer waters of clear and proper perspectives.

Principle of the Lat/Long system
 

On Sun, 4 Jan 2015 08:51:32 -0800 (PST), Gerald Kelleher
wrote:

On Sunday, January 4, 2015 8:35:33 AM UTC-8, Wayne. B wrote:
On Sun, 4 Jan 2015 07:06:49 -0800 (PST), Gerald Kelleher
wrote:

Having established the original method by which humans came to understand how the appearance of a star defined the Earth's orbital position around the Sun and the number of times it turns within the confines of that orbital circuit using an extra day and rotation over a 4 year period and 4 orbital circuits, the use of the average day and modern timekeeping comes into view. No better person than the great John Harrison to explain the principles -

"The application of a Timekeeper to this discovery is founded upon the
following principles: the earth's surface is divided into 360 equal parts (by imaginary lines drawn from North to South) which are called Degrees of Longitude; and its daily revolution Eastward round its own axis is performed in 24 hours; consequently in that period, each of those imaginary lines or degrees, becomes successively opposite to the Sun (which makes the noon or precise middle of the day at each of those degrees;) and it must follow, that from the time any one of those lines passes the Sun, till the next passes, must be just four minutes, for 24 hours being divided by 360 will give that quantity; so that for every degree of Longitude we sail Westward, it will be noon with us four minutes the later, and for every degree Eastward four minutes the sooner, and so on in proportion for any greater or less quantity. Now, the exact time of the day at the place where we are, can be ascertained by well known and easy observations of the Sun if visible for a few minutes at any
time
from his being ten degrees high until within an hour of noon, or from an hour after noon until he is only 10 degrees high in the afternoon; if therefore, at any time when such observation is made, a Timekeeper tells us at the same moment what o'clock it is at the place we sailed from, our Longitude is
clearly discovered." John Harrison

So here we have the 24 hour day linked to the passage of the Sun across the meridian each day where one rotation and one day always keep in step and especially February 29th which represents the older astronomical achievement that pins the Earth to its orbital position.

The next explanation is intricate but if readers can follow the principles so far that anchor the 24 hour day to rotation there is little that can go wrong understanding the next step which ties the Lat/Long system to the 24 hour AM/PM system.

===

Good grief, we've been dealing with imaginary boats on this group for
years. Now we have to deal with imaginary lines also? I've seen
those lines and they are just as real as Harry's boats.

What you may take for granted in a joking way would have been a serious issue at one stage in history -

http://en.wikipedia.org/wiki/Scilly_...saster_of_1707

The connection between the Lat/Long system along with timekeeping and how it meshes with planetary daily and orbital dynamics has never been explained properly hence this thread.

Anyone with the confidence of a skipper would have no problem so far with the explanation but we are sailing into stormy conceptual waters soon before returning to calmer waters of clear and proper perspectives.

===

As a self proclaimed expert in these matters, I assume you have also
read "Longtitude" by Daba Sobel and "The American Practical Navigator"
by Nathaniel Bowditch. There is a wealth of information in both.

Principle of the Lat/Long system
 

On 1/4/2015 11:51 AM, Gerald Kelleher wrote:
On Sunday, January 4, 2015 8:35:33 AM UTC-8, Wayne. B wrote:
On Sun, 4 Jan 2015 07:06:49 -0800 (PST), Gerald Kelleher
wrote:

Having established the original method by which humans came to understand how the appearance of a star defined the Earth's orbital position around the Sun and the number of times it turns within the confines of that orbital circuit using an extra day and rotation over a 4 year period and 4 orbital circuits, the use of the average day and modern timekeeping comes into view. No better person than the great John Harrison to explain the principles -

"The application of a Timekeeper to this discovery is founded upon the
following principles: the earth's surface is divided into 360 equal parts (by imaginary lines drawn from North to South) which are called Degrees of Longitude; and its daily revolution Eastward round its own axis is performed in 24 hours; consequently in that period, each of those imaginary lines or degrees, becomes successively opposite to the Sun (which makes the noon or precise middle of the day at each of those degrees;) and it must follow, that from the time any one of those lines passes the Sun, till the next passes, must be just four minutes, for 24 hours being divided by 360 will give that quantity; so that for every degree of Longitude we sail Westward, it will be noon with us four minutes the later, and for every degree Eastward four minutes the sooner, and so on in proportion for any greater or less quantity. Now, the exact time of the day at the place where we are, can be ascertained by well known and easy observations of the Sun if visible for a few minutes at any t
ime
from his being ten degrees high until within an hour of noon, or from an hour after noon until he is only 10 degrees high in the afternoon; if therefore, at any time when such observation is made, a Timekeeper tells us at the same moment what o'clock it is at the place we sailed from, our Longitude is
clearly discovered." John Harrison

So here we have the 24 hour day linked to the passage of the Sun across the meridian each day where one rotation and one day always keep in step and especially February 29th which represents the older astronomical achievement that pins the Earth to its orbital position.

The next explanation is intricate but if readers can follow the principles so far that anchor the 24 hour day to rotation there is little that can go wrong understanding the next step which ties the Lat/Long system to the 24 hour AM/PM system.

===

Good grief, we've been dealing with imaginary boats on this group for
years. Now we have to deal with imaginary lines also? I've seen
those lines and they are just as real as Harry's boats.

What you may take for granted in a joking way would have been a serious issue at one stage in history -

http://en.wikipedia.org/wiki/Scilly_...saster_of_1707

The connection between the Lat/Long system along with timekeeping and how it meshes with planetary daily and orbital dynamics has never been explained properly hence this thread.

Anyone with the confidence of a skipper would have no problem so far with the explanation but we are sailing into stormy conceptual waters soon before returning to calmer waters of clear and proper perspectives.


I am guessing most of this is way beyond my pay grade... :)

Principle of the Lat/Long system
 

On Sunday, January 4, 2015 10:12:13 AM UTC-8, KC wrote:
On 1/4/2015 11:51 AM, Gerald Kelleher wrote:
On Sunday, January 4, 2015 8:35:33 AM UTC-8, Wayne. B wrote:
On Sun, 4 Jan 2015 07:06:49 -0800 (PST), Gerald Kelleher
wrote:

Having established the original method by which humans came to understand how the appearance of a star defined the Earth's orbital position around the Sun and the number of times it turns within the confines of that orbital circuit using an extra day and rotation over a 4 year period and 4 orbital circuits, the use of the average day and modern timekeeping comes into view. No better person than the great John Harrison to explain the principles -

"The application of a Timekeeper to this discovery is founded upon the
following principles: the earth's surface is divided into 360 equal parts (by imaginary lines drawn from North to South) which are called Degrees of Longitude; and its daily revolution Eastward round its own axis is performed in 24 hours; consequently in that period, each of those imaginary lines or degrees, becomes successively opposite to the Sun (which makes the noon or precise middle of the day at each of those degrees;) and it must follow, that from the time any one of those lines passes the Sun, till the next passes, must be just four minutes, for 24 hours being divided by 360 will give that quantity; so that for every degree of Longitude we sail Westward, it will be noon with us four minutes the later, and for every degree Eastward four minutes the sooner, and so on in proportion for any greater or less quantity. Now, the exact time of the day at the place where we are, can be ascertained by well known and easy observations of the Sun if visible for a few minutes at any t
ime
from his being ten degrees high until within an hour of noon, or from an hour after noon until he is only 10 degrees high in the afternoon; if therefore, at any time when such observation is made, a Timekeeper tells us at the same moment what o'clock it is at the place we sailed from, our Longitude is
clearly discovered." John Harrison

So here we have the 24 hour day linked to the passage of the Sun across the meridian each day where one rotation and one day always keep in step and especially February 29th which represents the older astronomical achievement that pins the Earth to its orbital position.

The next explanation is intricate but if readers can follow the principles so far that anchor the 24 hour day to rotation there is little that can go wrong understanding the next step which ties the Lat/Long system to the 24 hour AM/PM system.

===

Good grief, we've been dealing with imaginary boats on this group for
years. Now we have to deal with imaginary lines also? I've seen
those lines and they are just as real as Harry's boats.

What you may take for granted in a joking way would have been a serious issue at one stage in history -

http://en.wikipedia.org/wiki/Scilly_...saster_of_1707

The connection between the Lat/Long system along with timekeeping and how it meshes with planetary daily and orbital dynamics has never been explained properly hence this thread.

Anyone with the confidence of a skipper would have no problem so far with the explanation but we are sailing into stormy conceptual waters soon before returning to calmer waters of clear and proper perspectives.


I am guessing most of this is way beyond my pay grade... :)

Absolutely not. The only assumption I make is that people are interested in how the planetary daily and orbital cycles are the basis for timekeeping such as defining the Earth's orbital position in space by the appearance of a single star and the number of times the planet turns within an orbital circuit.

I don't mind the lighthearted poking about imaginary lines however the foundations of navigation using timekeeping developed along a specific path and involves key observations ,some of which were made in antiquity.

Principle of the Lat/Long system
 

On Sunday, January 4, 2015 9:55:04 AM UTC-8, Wayne. B wrote:
On Sun, 4 Jan 2015 08:51:32 -0800 (PST), Gerald Kelleher
wrote:

On Sunday, January 4, 2015 8:35:33 AM UTC-8, Wayne. B wrote:
On Sun, 4 Jan 2015 07:06:49 -0800 (PST), Gerald Kelleher
wrote:

Having established the original method by which humans came to understand how the appearance of a star defined the Earth's orbital position around the Sun and the number of times it turns within the confines of that orbital circuit using an extra day and rotation over a 4 year period and 4 orbital circuits, the use of the average day and modern timekeeping comes into view. No better person than the great John Harrison to explain the principles -

"The application of a Timekeeper to this discovery is founded upon the
following principles: the earth's surface is divided into 360 equal parts (by imaginary lines drawn from North to South) which are called Degrees of Longitude; and its daily revolution Eastward round its own axis is performed in 24 hours; consequently in that period, each of those imaginary lines or degrees, becomes successively opposite to the Sun (which makes the noon or precise middle of the day at each of those degrees;) and it must follow, that from the time any one of those lines passes the Sun, till the next passes, must be just four minutes, for 24 hours being divided by 360 will give that quantity; so that for every degree of Longitude we sail Westward, it will be noon with us four minutes the later, and for every degree Eastward four minutes the sooner, and so on in proportion for any greater or less quantity. Now, the exact time of the day at the place where we are, can be ascertained by well known and easy observations of the Sun if visible for a few minutes at any
time
from his being ten degrees high until within an hour of noon, or from an hour after noon until he is only 10 degrees high in the afternoon; if therefore, at any time when such observation is made, a Timekeeper tells us at the same moment what o'clock it is at the place we sailed from, our Longitude is
clearly discovered." John Harrison

So here we have the 24 hour day linked to the passage of the Sun across the meridian each day where one rotation and one day always keep in step and especially February 29th which represents the older astronomical achievement that pins the Earth to its orbital position.

The next explanation is intricate but if readers can follow the principles so far that anchor the 24 hour day to rotation there is little that can go wrong understanding the next step which ties the Lat/Long system to the 24 hour AM/PM system.

===

Good grief, we've been dealing with imaginary boats on this group for
years. Now we have to deal with imaginary lines also? I've seen
those lines and they are just as real as Harry's boats.

What you may take for granted in a joking way would have been a serious issue at one stage in history -

http://en.wikipedia.org/wiki/Scilly_...saster_of_1707

The connection between the Lat/Long system along with timekeeping and how it meshes with planetary daily and orbital dynamics has never been explained properly hence this thread.

Anyone with the confidence of a skipper would have no problem so far with the explanation but we are sailing into stormy conceptual waters soon before returning to calmer waters of clear and proper perspectives.

===

As a self proclaimed expert in these matters, I assume you have also
read "Longtitude" by Daba Sobel and "The American Practical Navigator"
by Nathaniel Bowditch. There is a wealth of information in both.

In this case, anyone who wishes to follow the narrative must also reason from observations made possible by 21st century tools such as imaging and graphics.

It is crucial that the founding principle of timekeeping where an extra day and rotation is added after four 365 cycles corresponding to 4 orbital circuits of the Earth around the Sun is understood thoroughly but I personally don't envisage any problem with that.

The first appearance of Sirius (heliacal rising) just far enough to one side of the Sun to be seen one morning is a line-of-sight observation as the Earth moves around the Sun and the star is periodically lost behind its glare -

https://www.youtube.com/watch?v=eeQwYrfmvoQ

http://www.gautschy.ch/~rita/archast...liacsirius.JPG

A teacher should,by right, should be capable of answering a student's question as to why February 29th as both a day and as a rotation is required much less navigators who rely on the Lat/Long system as an extension of planetary dynamics and timekeeping.

I suspect many are new to this reasoning so every incentive to give it more consideration.

Principle of the Lat/Long system
 

On 1/4/2015 2:11 PM, Gerald Kelleher wrote:
On Sunday, January 4, 2015 10:12:13 AM UTC-8, KC wrote:
On 1/4/2015 11:51 AM, Gerald Kelleher wrote:
On Sunday, January 4, 2015 8:35:33 AM UTC-8, Wayne. B wrote:
On Sun, 4 Jan 2015 07:06:49 -0800 (PST), Gerald Kelleher
wrote:

Having established the original method by which humans came to understand how the appearance of a star defined the Earth's orbital position around the Sun and the number of times it turns within the confines of that orbital circuit using an extra day and rotation over a 4 year period and 4 orbital circuits, the use of the average day and modern timekeeping comes into view. No better person than the great John Harrison to explain the principles -

"The application of a Timekeeper to this discovery is founded upon the
following principles: the earth's surface is divided into 360 equal parts (by imaginary lines drawn from North to South) which are called Degrees of Longitude; and its daily revolution Eastward round its own axis is performed in 24 hours; consequently in that period, each of those imaginary lines or degrees, becomes successively opposite to the Sun (which makes the noon or precise middle of the day at each of those degrees;) and it must follow, that from the time any one of those lines passes the Sun, till the next passes, must be just four minutes, for 24 hours being divided by 360 will give that quantity; so that for every degree of Longitude we sail Westward, it will be noon with us four minutes the later, and for every degree Eastward four minutes the sooner, and so on in proportion for any greater or less quantity. Now, the exact time of the day at the place where we are, can be ascertained by well known and easy observations of the Sun if visible for a few minutes at any
t
ime
from his being ten degrees high until within an hour of noon, or from an hour after noon until he is only 10 degrees high in the afternoon; if therefore, at any time when such observation is made, a Timekeeper tells us at the same moment what o'clock it is at the place we sailed from, our Longitude is
clearly discovered." John Harrison

So here we have the 24 hour day linked to the passage of the Sun across the meridian each day where one rotation and one day always keep in step and especially February 29th which represents the older astronomical achievement that pins the Earth to its orbital position.

The next explanation is intricate but if readers can follow the principles so far that anchor the 24 hour day to rotation there is little that can go wrong understanding the next step which ties the Lat/Long system to the 24 hour AM/PM system.

===

Good grief, we've been dealing with imaginary boats on this group for
years. Now we have to deal with imaginary lines also? I've seen
those lines and they are just as real as Harry's boats.

What you may take for granted in a joking way would have been a serious issue at one stage in history -

http://en.wikipedia.org/wiki/Scilly_...saster_of_1707

The connection between the Lat/Long system along with timekeeping and how it meshes with planetary daily and orbital dynamics has never been explained properly hence this thread.

Anyone with the confidence of a skipper would have no problem so far with the explanation but we are sailing into stormy conceptual waters soon before returning to calmer waters of clear and proper perspectives.


I am guessing most of this is way beyond my pay grade... :)

Absolutely not. The only assumption I make is that people are interested in how the planetary daily and orbital cycles are the basis for timekeeping such as defining the Earth's orbital position in space by the appearance of a single star and the number of times the planet turns within an orbital circuit.

I don't mind the lighthearted poking about imaginary lines however the foundations of navigation using timekeeping developed along a specific path and involves key observations ,some of which were made in antiquity.





I wouldn't worry about it too much. We're probably good for another 100
years or so ....

http://en.wikipedia.org/wiki/Atomic_clock

Principle of the Lat/Long system
 

Gerald Kelleher wrote:
On Sunday, January 4, 2015 10:12:13 AM UTC-8, KC wrote:
On 1/4/2015 11:51 AM, Gerald Kelleher wrote:
On Sunday, January 4, 2015 8:35:33 AM UTC-8, Wayne. B wrote:
On Sun, 4 Jan 2015 07:06:49 -0800 (PST), Gerald Kelleher
wrote:

Having established the original method by which humans came to
understand how the appearance of a star defined the Earth's orbital
position around the Sun and the number of times it turns within the
confines of that orbital circuit using an extra day and rotation over
a 4 year period and 4 orbital circuits, the use of the average day
and modern timekeeping comes into view. No better person than the
great John Harrison to explain the principles -

"The application of a Timekeeper to this discovery is founded upon the
following principles: the earth's surface is divided into 360 equal
parts (by imaginary lines drawn from North to South) which are called
Degrees of Longitude; and its daily revolution Eastward round its own
axis is performed in 24 hours; consequently in that period, each of
those imaginary lines or degrees, becomes successively opposite to
the Sun (which makes the noon or precise middle of the day at each of
those degrees;) and it must follow, that from the time any one of
those lines passes the Sun, till the next passes, must be just four
minutes, for 24 hours being divided by 360 will give that quantity;
so that for every degree of Longitude we sail Westward, it will be
noon with us four minutes the later, and for every degree Eastward
four minutes the sooner, and so on in proportion for any greater or
less quantity. Now, the exact time of the day at the place where we
are, can be ascertained by well known and easy observations of the
Sun if visible for a few minutes at any t
ime
from his being ten degrees high until within an hour of noon, or from
an hour after noon until he is only 10 degrees high in the afternoon;
if therefore, at any time when such observation is made, a Timekeeper
tells us at the same moment what o'clock it is at the place we sailed
from, our Longitude is
clearly discovered." John Harrison

So here we have the 24 hour day linked to the passage of the Sun
across the meridian each day where one rotation and one day always
keep in step and especially February 29th which represents the older
astronomical achievement that pins the Earth to its orbital position.

The next explanation is intricate but if readers can follow the
principles so far that anchor the 24 hour day to rotation there is
little that can go wrong understanding the next step which ties the
Lat/Long system to the 24 hour AM/PM system.

==
Good grief, we've been dealing with imaginary boats on this group for
years. Now we have to deal with imaginary lines also? I've seen
those lines and they are just as real as Harry's boats.

What you may take for granted in a joking way would have been a serious
issue at one stage in history -

http://en.wikipedia.org/wiki/Scilly_...saster_of_1707

The connection between the Lat/Long system along with timekeeping and
how it meshes with planetary daily and orbital dynamics has never been
explained properly hence this thread.

Anyone with the confidence of a skipper would have no problem so far
with the explanation but we are sailing into stormy conceptual waters
soon before returning to calmer waters of clear and proper perspectives.


I am guessing most of this is way beyond my pay grade... :)

Absolutely not. The only assumption I make is that people are interested
in how the planetary daily and orbital cycles are the basis for
timekeeping such as defining the Earth's orbital position in space by the
appearance of a single star and the number of times the planet turns
within an orbital circuit.

I don't mind the lighthearted poking about imaginary lines however the
foundations of navigation using timekeeping developed along a specific
path and involves key observations ,some of which were made in antiquity.

Until there was a dependable shipboard clock, longitude was not really able
to be calculated while at sea.

Principle of the Lat/Long system
 

wrote:
On Sat, 03 Jan 2015 23:27:05 -0600, Califbill
wrote:

wrote:
On Sat, 3 Jan 2015 08:14:26 -0800 (PST),
wrote:

This is the broadest possible overview for those who are unfamiliar with
how the motions of the Earth fit in with human timekeeping and although
it is an injustice to those people who created the system we use today,
the overview is much better than none at all. There is no stopping to
differentiate between the original geocentric astronomers and their
observations from the later heliocentric astronomers who worked off the
idea that the Earth moves between Venus and Mars around the Sun so
readers today don't concern themselves with the level of knowledge of
any given era as this will be taken for granted in order to move the story along.

As the Earth moves through space in its circuit around the Sun,certain
stars lying on or near the same plane as the Earth's orbital motion are
temporarily lost behind the Sun's glare. The older astronomers marked
the passage as the Sun through the constellations (hence birth signs)
but for purposes of this story it is better to consider the apparent
motion of the stars behind the Sun due to the orbital motion of the Earth -

https://www.youtube.com/watch?v=eeQwYrfmvoQ

The anchor for the Lat/Long system originally was based on the
appearance of one particular star as the orbital motion of the Earth
placed the star just far enough to one side of the Sun one morning, That
star was the brightest one in the celestial arena known as Sirius and
can be seen on the bottom left of the image -

https://www.youtube.com/watch?v=eeQwYrfmvoQ

".. on account of the procession of the rising of Sirius by one day in
the course of 4 years,.. therefore it shall be, that the year of 360
days and the 5 days added to their end, so one day shall be from this
day after every 4 years added to the 5 epagomenae before the new year"
Canopus Decree 238 BC

Unbeknownst to themselves, what the Egyptians were actually doing was
defining the Earth's orbital position around the Sun using the seasonal
appearance of a star as a gauge and the number of rotations that fit
inside an orbital circuit, in this case 1461 rotations for 4 orbital
circuits which breaks down into 365 1/4 rotations to one orbital circuit.

This is the founding principle where one 24 hour day keeps in step with
one rotation of the Earth and the basis of the Lat/Long system along
with the reason why the extra day and rotation is introduced in order to
keep the Earth's position in space fixed by the number of rotations,at
least to the nearest rotation.

The next step is the process which equates the 'average' 24 hour day
with 'constant' rotation insofar as the average 24 hour day substitutes
for constant rotation through 360 degrees in that period.






I am reacquainting myself with celestial mechanics as I am playing
with my new sextant.

I inherited an airplane sextant and only tried to play with it once. Has a
disk that a pencil lead marks to get an average of the horizon in a moving
airplane. Is missing the degree wheel I think.

I am reading a book on sextants that talks about a bubble attachment
for aircraft use but they are spendy.
I am going to have to get to the gulf to see a real horizon so I will
be playing with artificial ones here. There are a number of them in
the book, starting with a simple pan of oil.

It is an ANSCO. A-10A

Principle of the Lat/Long system
 

On Sunday, January 4, 2015 12:04:49 PM UTC-8, Califbill wrote:
Gerald Kelleher wrote:
On Sunday, January 4, 2015 10:12:13 AM UTC-8, KC wrote:
On 1/4/2015 11:51 AM, Gerald Kelleher wrote:
On Sunday, January 4, 2015 8:35:33 AM UTC-8, Wayne. B wrote:
On Sun, 4 Jan 2015 07:06:49 -0800 (PST), Gerald Kelleher
wrote:

Having established the original method by which humans came to
understand how the appearance of a star defined the Earth's orbital
position around the Sun and the number of times it turns within the
confines of that orbital circuit using an extra day and rotation over
a 4 year period and 4 orbital circuits, the use of the average day
and modern timekeeping comes into view. No better person than the
great John Harrison to explain the principles -

"The application of a Timekeeper to this discovery is founded upon the
following principles: the earth's surface is divided into 360 equal
parts (by imaginary lines drawn from North to South) which are called
Degrees of Longitude; and its daily revolution Eastward round its own
axis is performed in 24 hours; consequently in that period, each of
those imaginary lines or degrees, becomes successively opposite to
the Sun (which makes the noon or precise middle of the day at each of
those degrees;) and it must follow, that from the time any one of
those lines passes the Sun, till the next passes, must be just four
minutes, for 24 hours being divided by 360 will give that quantity;
so that for every degree of Longitude we sail Westward, it will be
noon with us four minutes the later, and for every degree Eastward
four minutes the sooner, and so on in proportion for any greater or
less quantity. Now, the exact time of the day at the place where we
are, can be ascertained by well known and easy observations of the
Sun if visible for a few minutes at any t
ime
from his being ten degrees high until within an hour of noon, or from
an hour after noon until he is only 10 degrees high in the afternoon;
if therefore, at any time when such observation is made, a Timekeeper
tells us at the same moment what o'clock it is at the place we sailed
from, our Longitude is
clearly discovered." John Harrison

So here we have the 24 hour day linked to the passage of the Sun
across the meridian each day where one rotation and one day always
keep in step and especially February 29th which represents the older
astronomical achievement that pins the Earth to its orbital position.

Principle of the Lat/Long system
 

Gerald Kelleher wrote:
On Sunday, January 4, 2015 12:04:49 PM UTC-8, Califbill wrote:
Gerald Kelleher wrote:
On Sunday, January 4, 2015 10:12:13 AM UTC-8, KC wrote:
On 1/4/2015 11:51 AM, Gerald Kelleher wrote:
On Sunday, January 4, 2015 8:35:33 AM UTC-8, Wayne. B wrote:
On Sun, 4 Jan 2015 07:06:49 -0800 (PST), Gerald Kelleher
wrote:

Having established the original method by which humans came to
understand how the appearance of a star defined the Earth's orbital
position around the Sun and the number of times it turns within the
confines of that orbital circuit using an extra day and rotation over
a 4 year period and 4 orbital circuits, the use of the average day
and modern timekeeping comes into view. No better person than the
great John Harrison to explain the principles -

"The application of a Timekeeper to this discovery is founded upon the
following principles: the earth's surface is divided into 360 equal
parts (by imaginary lines drawn from North to South) which are called
Degrees of Longitude; and its daily revolution Eastward round its own
axis is performed in 24 hours; consequently in that period, each of
those imaginary lines or degrees, becomes successively opposite to
the Sun (which makes the noon or precise middle of the day at each of
those degrees;) and it must follow, that from the time any one of
those lines passes the Sun, till the next passes, must be just four
minutes, for 24 hours being divided by 360 will give that quantity;
so that for every degree of Longitude we sail Westward, it will be
noon with us four minutes the later, and for every degree Eastward
four minutes the sooner, and so on in proportion for any greater or
less quantity. Now, the exact time of the day at the place where we
are, can be ascertained by well known and easy observations of the
Sun if visible for a few minutes at any t
ime
from his being ten degrees high until within an hour of noon, or from
an hour after noon until he is only 10 degrees high in the afternoon;
if therefore, at any time when such observation is made, a Timekeeper
tells us at the same moment what o'clock it is at the place we sailed
from, our Longitude is
clearly discovered." John Harrison

So here we have the 24 hour day linked to the passage of the Sun
across the meridian each day where one rotation and one day always
keep in step and especially February 29th which represents the older
astronomical achievement that pins the Earth to its orbital position.

The next explanation is intricate but if readers can follow the
principles so far that anchor the 24 hour day to rotation there is
little that can go wrong understanding the next step which ties the
Lat/Long system to the 24 hour AM/PM system.

==
Good grief, we've been dealing with imaginary boats on this group for
years. Now we have to deal with imaginary lines also? I've seen
those lines and they are just as real as Harry's boats.

What you may take for granted in a joking way would have been a serious
issue at one stage in history -

http://en.wikipedia.org/wiki/Scilly_...saster_of_1707

The connection between the Lat/Long system along with timekeeping and
how it meshes with planetary daily and orbital dynamics has never been
explained properly hence this thread.

Anyone with the confidence of a skipper would have no problem so far
with the explanation but we are sailing into stormy conceptual waters
soon before returning to calmer waters of clear and proper perspectives.


I am guessing most of this is way beyond my pay grade... :)

Absolutely not. The only assumption I make is that people are interested
in how the planetary daily and orbital cycles are the basis for
timekeeping such as defining the Earth's orbital position in space by the
appearance of a single star and the number of times the planet turns
within an orbital circuit.

I don't mind the lighthearted poking about imaginary lines however the
foundations of navigation using timekeeping developed along a specific
path and involves key observations ,some of which were made in antiquity.

Until there was a dependable shipboard clock, longitude was not really able
to be calculated while at sea.

This is the later part of the story that most hear through the
innovations of John Harrison however these stories only pay minimal
attention to the foundations of timekeeping and where it meshes with the
daily and orbital motions of the Earth.

The idea being that one 24 hour day and one full rotation of the planet
keep in step so that observers can assign significance to February 29th
in terms of the number of times the planet turns inside an orbital
circuit, in this case 1461 rotations across 4 orbital circuits or 365 1/4
rotations to one orbital circuit.

The Lat/Long system is dependent on the daily motion of the Sun crossing
the meridian and this includes the extra day and rotation after four
periods of 365 days. This is important when venturing into errors that
were made in the late 17th century.

Also depends on leap years and leap years without a leap day. And probably
also required a printing press to get the tables distributed widely. All
part of advancement. The Vikings had a compass, which was a secret from
others.

Principle of the Lat/Long system
 

On Sun, 04 Jan 2015 14:07:26 -0500, wrote:

On Sun, 04 Jan 2015 12:54:12 -0500, Wayne.B
wrote:

On Sun, 4 Jan 2015 08:51:32 -0800 (PST), Gerald Kelleher
wrote:

On Sunday, January 4, 2015 8:35:33 AM UTC-8, Wayne. B wrote:
On Sun, 4 Jan 2015 07:06:49 -0800 (PST), Gerald Kelleher
wrote:

Having established the original method by which humans came to understand how the appearance of a star defined the Earth's orbital position around the Sun and the number of times it turns within the confines of that orbital circuit using an extra day and rotation over a 4 year period and 4 orbital circuits, the use of the average day and modern timekeeping comes into view. No better person than the great John Harrison to explain the principles -

"The application of a Timekeeper to this discovery is founded upon the
following principles: the earth's surface is divided into 360 equal parts (by imaginary lines drawn from North to South) which are called Degrees of Longitude; and its daily revolution Eastward round its own axis is performed in 24 hours; consequently in that period, each of those imaginary lines or degrees, becomes successively opposite to the Sun (which makes the noon or precise middle of the day at each of those degrees;) and it must follow, that from the time any one of those lines passes the Sun, till the next passes, must be just four minutes, for 24 hours being divided by 360 will give that quantity; so that for every degree of Longitude we sail Westward, it will be noon with us four minutes the later, and for every degree Eastward four minutes the sooner, and so on in proportion for any greater or less quantity. Now, the exact time of the day at the place where we are, can be ascertained by well known and easy observations of the Sun if visible for a few minutes at any
time
from his being ten degrees high until within an hour of noon, or from an hour after noon until he is only 10 degrees high in the afternoon; if therefore, at any time when such observation is made, a Timekeeper tells us at the same moment what o'clock it is at the place we sailed from, our Longitude is
clearly discovered." John Harrison

So here we have the 24 hour day linked to the passage of the Sun across the meridian each day where one rotation and one day always keep in step and especially February 29th which represents the older astronomical achievement that pins the Earth to its orbital position.

The next explanation is intricate but if readers can follow the principles so far that anchor the 24 hour day to rotation there is little that can go wrong understanding the next step which ties the Lat/Long system to the 24 hour AM/PM system.

===

Good grief, we've been dealing with imaginary boats on this group for
years. Now we have to deal with imaginary lines also? I've seen
those lines and they are just as real as Harry's boats.

What you may take for granted in a joking way would have been a serious issue at one stage in history -

http://en.wikipedia.org/wiki/Scilly_...saster_of_1707

The connection between the Lat/Long system along with timekeeping and how it meshes with planetary daily and orbital dynamics has never been explained properly hence this thread.

Anyone with the confidence of a skipper would have no problem so far with the explanation but we are sailing into stormy conceptual waters soon before returning to calmer waters of clear and proper perspectives.

===

As a self proclaimed expert in these matters, I assume you have also
read "Longtitude" by Daba Sobel and "The American Practical Navigator"
by Nathaniel Bowditch. There is a wealth of information in both.

Bowditch is certainly the gold standard but the 1414 pages of volume 1
and 961 of volume 2 may be a little intimidating.

===

Darn good reading though if you're seriously interested in navigation.
My copies are about 40 years old and almost worn out from being
carried around on my various sailboats over the years.

Principle of the Lat/Long system
 

On Sunday, January 4, 2015 11:45:24 AM UTC-8, Mr. Luddite wrote:
On 1/4/2015 2:11 PM, Gerald Kelleher wrote:
On Sunday, January 4, 2015 10:12:13 AM UTC-8, KC wrote:
On 1/4/2015 11:51 AM, Gerald Kelleher wrote:
On Sunday, January 4, 2015 8:35:33 AM UTC-8, Wayne. B wrote:
On Sun, 4 Jan 2015 07:06:49 -0800 (PST), Gerald Kelleher
wrote:

Having established the original method by which humans came to understand how the appearance of a star defined the Earth's orbital position around the Sun and the number of times it turns within the confines of that orbital circuit using an extra day and rotation over a 4 year period and 4 orbital circuits, the use of the average day and modern timekeeping comes into view. No better person than the great John Harrison to explain the principles -

"The application of a Timekeeper to this discovery is founded upon the
following principles: the earth's surface is divided into 360 equal parts (by imaginary lines drawn from North to South) which are called Degrees of Longitude; and its daily revolution Eastward round its own axis is performed in 24 hours; consequently in that period, each of those imaginary lines or degrees, becomes successively opposite to the Sun (which makes the noon or precise middle of the day at each of those degrees;) and it must follow, that from the time any one of those lines passes the Sun, till the next passes, must be just four minutes, for 24 hours being divided by 360 will give that quantity; so that for every degree of Longitude we sail Westward, it will be noon with us four minutes the later, and for every degree Eastward four minutes the sooner, and so on in proportion for any greater or less quantity. Now, the exact time of the day at the place where we are, can be ascertained by well known and easy observations of the Sun if visible for a few minutes at any
t
ime
from his being ten degrees high until within an hour of noon, or from an hour after noon until he is only 10 degrees high in the afternoon; if therefore, at any time when such observation is made, a Timekeeper tells us at the same moment what o'clock it is at the place we sailed from, our Longitude is
clearly discovered." John Harrison

So here we have the 24 hour day linked to the passage of the Sun across the meridian each day where one rotation and one day always keep in step and especially February 29th which represents the older astronomical achievement that pins the Earth to its orbital position.

The next explanation is intricate but if readers can follow the principles so far that anchor the 24 hour day to rotation there is little that can go wrong understanding the next step which ties the Lat/Long system to the 24 hour AM/PM system.

===

Good grief, we've been dealing with imaginary boats on this group for
years. Now we have to deal with imaginary lines also? I've seen
those lines and they are just as real as Harry's boats.

What you may take for granted in a joking way would have been a serious issue at one stage in history -

http://en.wikipedia.org/wiki/Scilly_...saster_of_1707

The connection between the Lat/Long system along with timekeeping and how it meshes with planetary daily and orbital dynamics has never been explained properly hence this thread.

Anyone with the confidence of a skipper would have no problem so far with the explanation but we are sailing into stormy conceptual waters soon before returning to calmer waters of clear and proper perspectives.


I am guessing most of this is way beyond my pay grade... :)

Absolutely not. The only assumption I make is that people are interested in how the planetary daily and orbital cycles are the basis for timekeeping such as defining the Earth's orbital position in space by the appearance of a single star and the number of times the planet turns within an orbital circuit.

I don't mind the lighthearted poking about imaginary lines however the foundations of navigation using timekeeping developed along a specific path and involves key observations ,some of which were made in antiquity.





I wouldn't worry about it too much. We're probably good for another 100
years or so ....

http://en.wikipedia.org/wiki/Atomic_clock

The issue is not just the Lat/Long system working in tandem with the 24 hour system but also how the original framework was created by defining the Earth's orbital position in space using an annual astronomical event as Sirius comes into view after a period behind the glare of the Sun. The determination is made using the number of rotations hence it takes 4 annual circuits of the Sun to nail down the number of rotations to a close proportion.

To move the narrative on slightly - as one 24 day elapses into the next 24 hours it maintains a relationship to both the daily and orbital features of the Earth. The Lat/Long system is an extension the line-of-sight observation where a star will skip an appearance by one day and one rotation after four periods of 365 days .

The framework where one 24 hour day and one rotation keeps in step is dependent on the original observation which creates the leap day however this is only the beginning of the narrative.

Principle of the Lat/Long system
 

On Sun, 4 Jan 2015 19:18:41 -0800 (PST), Gerald Kelleher
wrote:

I don't mind the lighthearted poking about imaginary lines however the foundations of navigation using timekeeping developed along a specific path and involves key observations ,some of which were made in antiquity.





I wouldn't worry about it too much. We're probably good for another 100
years or so ....

http://en.wikipedia.org/wiki/Atomic_clock

The issue is not just the Lat/Long system working in tandem with the 24 hour system but also how the original framework was created by defining the Earth's orbital position in space using an annual astronomical event as Sirius comes into view after a period behind the glare of the Sun. The determination is made using the number of rotations hence it takes 4 annual circuits of the Sun to nail down the number of rotations to a close proportion.

To move the narrative on slightly - as one 24 day elapses into the next 24 hours it maintains a relationship to both the daily and orbital features of the Earth. The Lat/Long system is an extension the line-of-sight observation where a star will skip an appearance by one day and one rotation after four periods of 365 days .

The framework where one 24 hour day and one rotation keeps in step is dependent on the original observation which creates the leap day however this is only the beginning of the narrative.

===

Gerald, I'm curious to know how you happened to discover our little
group here. Welcome. It's good to see a new and relevant topic of
discussion. I have a great deal of respect and admiration for the
folks who made these observations and conclusions in antiquity. In
those days you could be burned at the stake just for stating that the
earth revolved around the sun instead of vice versa. It sometimes
took courage as well as intellect.

As you probably know, careful observation and recording of solar and
planetary motions ultimately paved the way for Newton's theories, and
modern day physics.

Principle of the Lat/Long system
 

This is great reading especially for the technically challenged like me. With my style of lake boating its more like " hey, let's go that away!"

Keep it coming though. This is all good to know...

Principle of the Lat/Long system
 

On Monday, January 5, 2015 6:09:51 AM UTC-8, Tim wrote:
This is great reading especially for the technically challenged like me. With my style of lake boating its more like " hey, let's go that away!"

Keep it coming though. This is all good to know...

Although the Egyptians knew nothing of daily rotation and the orbital motion of the Earth around the Sun, they realized that they could not base their year on a constant stream of 365 days. The flooding of Nile on which their culture depended coincided closely with the annual appearance of Sirius one morning hence their awareness of the brightest star in the celestial arena for practical reasons and the fact that it skips an appearance by one day after 4 years. In dynamical terms, the additional 24 hours represents the orbital distance the Earth needs to travel to bring Sirius back into view or what now has become the February 29th rotation. We omit 6 hours of orbital motion each non leap year as we gauge our day solely by daily rotation and this accumulates to roughly 24 hours of missing orbital distance at the end of 4 orbital circuits and 4 years.

It isn't really possible to continue with the narrative without an explanation which contains the leap day rotation and what it represents in dynamical terms. Perhaps another could explain it better and I have no objections to this however the facts will remain roughly the same.

The maritime tradition, much like astronomy, is among the most noble and ancient human endeavors in terms of sophistication so that people generally don't think of their ancestors in terms of primitive but rather look for the roots of contemporary traditions in older methods and insights. The rules governing navigation from boats to aircraft are one thing but the timekeeping systems on which navigation is based in something else and this requires some knowledge of the Earth's daily and orbital cycles.

Principle of the Lat/Long system
 

Gerald, it's all amazing isn't it?

Principle of the Lat/Long system
 

On Mon, 5 Jan 2015 07:48:20 -0800 (PST), Tim
wrote:

Gerald, it's all amazing isn't it?

===

It certainly is. Two years ago we visited the Mayan pyramids in
Chichén Itzá, Mexico. It turns out that the ancient Mayans were also
keen observers of celestial phenomena and had an onsite observatory
dedicated to those observations. They were aware of planetary
motions and relative orbits around the sun, including the fact that
Mars and Mercury were farther from the sun than Earth, and that Venus
and Mercury were closer. They also had a very accurate calendar
which took leap years into account. All of that was more than a
thousand years ago.

Principle of the Lat/Long system
 

Speaking of pyramids its my understanding the the 4 corners were at a true north south east and west ane with recent technology it's been proven that they were off byaybe a degree or so.

Principle of the Lat/Long system
 

Gerald Kelleher wrote:
On Monday, January 5, 2015 6:09:51 AM UTC-8, Tim wrote:
This is great reading especially for the technically challenged like me.
With my style of lake boating its more like " hey, let's go that away!"

Keep it coming though. This is all good to know...

Although the Egyptians knew nothing of daily rotation and the orbital
motion of the Earth around the Sun, they realized that they could not
base their year on a constant stream of 365 days. The flooding of Nile on
which their culture depended coincided closely with the annual appearance
of Sirius one morning hence their awareness of the brightest star in the
celestial arena for practical reasons and the fact that it skips an
appearance by one day after 4 years. In dynamical terms, the additional
24 hours represents the orbital distance the Earth needs to travel to
bring Sirius back into view or what now has become the February 29th
rotation. We omit 6 hours of orbital motion each non leap year as we
gauge our day solely by daily rotation and this accumulates to roughly 24
hours of missing orbital distance at the end of 4 orbital circuits and 4 years.

It isn't really possible to continue with the narrative without an
explanation which contains the leap day rotation and what it represents
in dynamical terms. Perhaps another could explain it better and I have no
objections to this however the facts will remain roughly the same.

The maritime tradition, much like astronomy, is among the most noble and
ancient human endeavors in terms of sophistication so that people
generally don't think of their ancestors in terms of primitive but rather
look for the roots of contemporary traditions in older methods and
insights. The rules governing navigation from boats to aircraft are one
thing but the timekeeping systems on which navigation is based in
something else and this requires some knowledge of the Earth's daily and orbital cycles.

The Egyptians may have known of the rotation and even of the orbit. Forget
which Egyptians calculated the diameter of the earth. They were only off
by about 225 miles, using sticks and shadows at a certain time. Way before
Europe and Rome admitted the earth was not flat.

Principle of the Lat/Long system
 

Tim wrote:
Speaking of pyramids its my understanding the the 4 corners were at a
true north south east and west ane with recent technology it's been
proven that they were off byaybe a degree or so.

You would expect true north and not magnetic north. Do not know if they
had magnetic compass. And they may have been very close as probably set
via star sightings and there has been some movement in a thousand years.

Principle of the Lat/Long system
 

In article 1917021474442175479.361632bmckeenospam-
, says...


The Egyptians may have known of the rotation and even of the orbit. Forget
which Egyptians calculated the diameter of the earth. They were only off
by about 225 miles, using sticks and shadows at a certain time. Way before
Europe and Rome admitted the earth was not flat.

It was Eratosthenes, a Greek. But he did hang out in Alexandria.

Principle of the Lat/Long system
 

Boating All Out wrote:
In article 1917021474442175479.361632bmckeenospam-
, says...


The Egyptians may have known of the rotation and even of the orbit. Forget
which Egyptians calculated the diameter of the earth. They were only off
by about 225 miles, using sticks and shadows at a certain time. Way before
Europe and Rome admitted the earth was not flat.

It was Eratosthenes, a Greek. But he did hang out in Alexandria.

Thanks. Been a long time since university.

Principle of the Lat/Long system
 

On Monday, January 5, 2015 7:48:22 AM UTC-8, Tim wrote:
Gerald, it's all amazing isn't it?

http://www.gautschy.ch/~rita/archast...liacsirius.JPG

To recap, when the Egyptians saw Sirius appear one morning after an absence behind the glare of the Sun for a few months they knew it would appear again 365 days later, yet again after another 365 days and then again on the third cycle of 365 days but on the fourth 365 day cycle Sirius was nowhere to be seen. It would appear the next day hence the extra rotation that we know as February 29th.

Each non leap year the Earth falls behind in position by 6 hours of orbital motion which accumulates to 12 hours after the second 365 day day cycle,18 hours after the third cycle and a full 24 hours on February 28th of a leap year. The extra rotation corresponds to 24 hours of orbital distance the Earth travels so that it completes 4 full orbital circuits using 1461 rotations as a gauge. This in turn reduces to 3651/4 rotations per circuit.

The next step is a fairly intricate one as the 24 hour day makes an appearance within this framework of 365/366 days.

Principle of the Lat/Long system
 

On Mon, 5 Jan 2015 07:48:20 -0800 (PST), Tim
wrote:

Gerald, it's all amazing isn't it?

And also amazing is that, according to some, it's all a random
occurrence from a big explosion.

Wow.

Principle of the Lat/Long system
 

On Monday, January 5, 2015 6:10:43 PM UTC-8, John H. wrote:
On Mon, 5 Jan 2015 07:48:20 -0800 (PST), Tim
wrote:

Gerald, it's all amazing isn't it?

And also amazing is that, according to some, it's all a random
occurrence from a big explosion.

Wow.

The words 'average' and 'constant' come into play at this juncture for the 'average' 24 hour day substitutes for 'constant' rotation at 15 degrees per hour or once in 24 hours. For instance, the average flow of a liquid through a pipe is the same thing as the constant flow of liquid through the same pipe however the timekeeping system uses 'average' as a starting point.

When accurate clocks started to emerge in the 17th century it was already known that with each sweep of the Sun across the observer's meridian, the total length of the day regardless of hemispheres varies from noon to noon. As each day corresponds to another rotation, a certain value was attached to each day to equalize it to a 24 hour average -

"Draw a Meridian line upon a floor and then hang two plummets, each by a small thread or wire, directly over the said Meridian, at the distance of some 2 feet or more one from the other, as the smallness of the thread will admit. When the middle of the Sun (the Eye being placed so, as to bring both the threads into one line) appears to be in the same line exactly you are then immediately to set the Watch, not precisely to the hour of 12 but by so much less, as is the Equation of the day by the Table." Huygens

http://adcs.home.xs4all.nl/Huygens/06/kort-E.html

So what readers have is one 24 hour day following the next 24 hour day, Monday turning into Tuesday,Tuesday into Wednesday and so on with the fact that each day corresponds to one rotation. The average 24 hour day then substitutes for the notion that the Earth's rotation is constant at a rate of 1 Degree per 4 minutes, 15 Degrees per hour and a rotation of the planet's 24901 circumference in 24 hours including the February 29th rotation.

Principle of the Lat/Long system
 

Most people when they wake up at dawn understand that the Sun rising and setting within each 24 hour period represents a rotation of our home planet while few people go into greater detail to comprehend the Lat/Long system overlaid on the geometry and geography of the Earth and tied to each rotation in 24 hours . Nobody goes into the details of planetary dynamics where the system which differentiates the rotation of the Earth 365 1/4 times per annual circuit from human timekeeping which formats the natural observation into the 365 day/366 day calendar framework.

We exist in an era where it is fashionable to say that the Earth turns 366 1/4 times within the confines of an orbital circuit thereby destroying the elegant reasoning which links timekeeping to the great planetary cycles of daily rotation and orbital motion -

"During one orbit around the Sun, the Earth rotates about its own axis 366.26 times" Main 'Earth' page, Wikipedia

http://en.wikipedia.org/wiki/Earth

Effectively people are prepared to believe that days and rotations fall out of step across an annual circuit which should be unthinkable for reasonable people let alone those involved in navigation and a familiarity with the Lat/Long system. How mistakes were made to give rise to a monstrous reasoning is second to understanding how the timekeeping system framework was constructed from observations of the Earth's motion and the parent observation that there are 1461 rotations within 4 orbital circuits which breaks down to 365 1/4 rotations per orbital circuit.

It is a question of relevance at this stage, how people value their own intellectual capabilities at the most basic level where they know that when they wake up to a new day they are also waking up to another rotation and they never,ever fall out of step.

Principle of the Lat/Long system
 

The quite understand the silence regarding this awful notion that there are 366 1/4 rotations inside an orbital circumference when,in fact, there are 365 1/4 with the latter correct value drawn from the parent observation of the additional February 29th rotation and what it represents in dynamical terms.

About 20 years ago anyone who picked up a textbook would have read that the Earth doesn't turn once in 24 hours but in 23 hours 56 minutes 04 seconds -

http://hypertextbook.com/facts/1999/JennyChen.shtml

The idea was that the extra 3 minutes 56 seconds to 24 hours accumulates over an orbital period and that generates the extra rotation than 24 hour days -

"During one orbit around the Sun, the Earth rotates about its own axis 366.26 times" Wikipedia main 'Earth' article

Like all catastrophic events where considerable damage and chaos ensues, the consequences are brutal including the inability to react to this situation where the emergence of the Lat/Long system in tandem with the 24 hour system keeps days and rotations in sync.

Today they even have created a new fiction conjured out of thin air in order to create a division between timekeeping and the rotation of the Earth where they now reject the 'solar vs sidereal' fiction and introduce a non cyclical and non astronomical assertion -

"At the time of the dinosaurs, Earth completed one rotation in about 23 hours," says MacMillan, who is a member of the VLBI team at NASA Goddard. "In the year 1820, a rotation took exactly 24 hours, or 86,400 standard seconds.." NASA

I hope reader here enjoyed the brief tour through to the historical and astronomical origins of timekeeping even in an era where men no longer believe that 24 hour days and rotations keep in step. Astronomy today is basically rudderless - an exercise in voodoo and bluffing created by academics and for academics while basic facts and enjoyable principles are ignored and even despised.

Principle of the Lat/Long system
 

There was a mention in this thread about burning at the stake for believing the Earth goes around the Sun referring to the Catholic Church and the events surrounding the Galileo affair. The real problem and valid objection of the Pope was how to prove the Earth turns using the same system which predicts astronomical events in that he believed it couldn't be done, at least according to a closer inspection of the issues separating Galileo and the Pope -

"Here lurked the danger of serious misunderstanding. Maffeo Barberini, while he was a Cardinal, had counselled Galileo to treat Copernicanism as a hypothesis, not as a confirmed truth. But 'hypothesis' meant two very different things. On the one hand, astronomers were assumed to deal only with hypotheses, i.e. accounts of the observed motions of the stars and planets that were not claimed to be true. Astronomical theories were mere instruments for calculation and prediction, a view that is often called 'instrumentalism'.. On the other hand, a hypothesis could also be understood as a theory that was not yet proved but was open to eventual confirmation. This was a 'realist' position. Galileo thought that Copernicanism was true, and presented it as a hypothesis, i.e. as a provisional idea that was potentially physically true, and he discussed the pros and cons, leaving the issue undecided. This did not correspond to the instrumentalist view of Copernicanism that was held by Maffeo Barberini and others. They thought that Copernicus' system was a purely instrumental device, and Maffeo Barberini was convinced that it could never be proved. This ambiguity pervaded the whole Galileo Affair."

http://www.unav.es/cryf/english/newlightistanbul.html

The parent observation of timekeeping where it meshes with planetary dynamics is with the leap day rotation and the 1461 rotations which fit inside 4 orbital circumferences. This fact goes in two separate directions - for interpretative astronomy where the Earth's motions and solar system structure is being researched and proved it reduces to 365 1/4 rotations per orbital circuit while for predictive astronomy where astronomical events are determined within the calendar framework the parent 1461 rotations are formatted in a 365/366 rotation scaffolding.

Sure,people can believe that Church doctrine was dependent on the Earth at the center of the Universe however a closer look at the issue reveals that the objections were quite valid. Only with 21st century tools can the issue be untangled and resolved but it can't be if contemporaries believe the Earth rotates 366 1/4 times inside one orbital circuit.

The Lat/Long system plays a crucial role in extracting humanity from an era mired in voodoo and bluff including the fuss over a 'leap second' -

http://www.abc.net.au/news/2015-01-0...r-year/6002002

Principle of the Lat/Long system
 

On Saturday, 3 January 2015 13:36:04 UTC-4, wrote:
On Sat, 3 Jan 2015 08:14:26 -0800 (PST),
wrote:

This is the broadest possible overview for those who are unfamiliar with how the motions of the Earth fit in with human timekeeping and although it is an injustice to those people who created the system we use today, the overview is much better than none at all. There is no stopping to differentiate between the original geocentric astronomers and their observations from the later heliocentric astronomers who worked off the idea that the Earth moves between Venus and Mars around the Sun so readers today don't concern themselves with the level of knowledge of any given era as this will be taken for granted in order to move the story along.

As the Earth moves through space in its circuit around the Sun,certain stars lying on or near the same plane as the Earth's orbital motion are temporarily lost behind the Sun's glare. The older astronomers marked the passage as the Sun through the constellations (hence birth signs) but for purposes of this story it is better to consider the apparent motion of the stars behind the Sun due to the orbital motion of the Earth -

https://www.youtube.com/watch?v=eeQwYrfmvoQ

The anchor for the Lat/Long system originally was based on the appearance of one particular star as the orbital motion of the Earth placed the star just far enough to one side of the Sun one morning, That star was the brightest one in the celestial arena known as Sirius and can be seen on the bottom left of the image -

https://www.youtube.com/watch?v=eeQwYrfmvoQ

".. on account of the procession of the rising of Sirius by one day in the course of 4 years,.. therefore it shall be, that the year of 360 days and the 5 days added to their end, so one day shall be from this day after every 4 years added to the 5 epagomenae before the new year" Canopus Decree 238 BC

Unbeknownst to themselves, what the Egyptians were actually doing was defining the Earth's orbital position around the Sun using the seasonal appearance of a star as a gauge and the number of rotations that fit inside an orbital circuit, in this case 1461 rotations for 4 orbital circuits which breaks down into 365 1/4 rotations to one orbital circuit.

This is the founding principle where one 24 hour day keeps in step with one rotation of the Earth and the basis of the Lat/Long system along with the reason why the extra day and rotation is introduced in order to keep the Earth's position in space fixed by the number of rotations,at least to the nearest rotation.

The next step is the process which equates the 'average' 24 hour day with 'constant' rotation insofar as the average 24 hour day substitutes for constant rotation through 360 degrees in that period.






I am reacquainting myself with celestial mechanics as I am playing
with my new sextant.


I've thought about buying the Davis 25 plastic sextant to play with. one practical use would be to confirm the height of the huge Linden trees that border my back yard.
I did a google search and found a link that described how you could estimate height with an upside down protractor, a string with a weighted object as a kind of plumb bob and a ruler to sight along.The ruler would sit on the upside down base of the protractor and the string would give you the sighted angle. The guy provided the formula to get a fairly accurate height.

Principle of the Lat/Long system
 

On 1/8/2015 11:05 AM, True North wrote:
On Saturday, 3 January 2015 13:36:04 UTC-4, wrote:
On Sat, 3 Jan 2015 08:14:26 -0800 (PST),
wrote:

This is the broadest possible overview for those who are unfamiliar with how the motions of the Earth fit in with human timekeeping and although it is an injustice to those people who created the system we use today, the overview is much better than none at all. There is no stopping to differentiate between the original geocentric astronomers and their observations from the later heliocentric astronomers who worked off the idea that the Earth moves between Venus and Mars around the Sun so readers today don't concern themselves with the level of knowledge of any given era as this will be taken for granted in order to move the story along.

As the Earth moves through space in its circuit around the Sun,certain stars lying on or near the same plane as the Earth's orbital motion are temporarily lost behind the Sun's glare. The older astronomers marked the passage as the Sun through the constellations (hence birth signs) but for purposes of this story it is better to consider the apparent motion of the stars behind the Sun due to the orbital motion of the Earth -

https://www.youtube.com/watch?v=eeQwYrfmvoQ

The anchor for the Lat/Long system originally was based on the appearance of one particular star as the orbital motion of the Earth placed the star just far enough to one side of the Sun one morning, That star was the brightest one in the celestial arena known as Sirius and can be seen on the bottom left of the image -

https://www.youtube.com/watch?v=eeQwYrfmvoQ

".. on account of the procession of the rising of Sirius by one day in the course of 4 years,.. therefore it shall be, that the year of 360 days and the 5 days added to their end, so one day shall be from this day after every 4 years added to the 5 epagomenae before the new year" Canopus Decree 238 BC

Unbeknownst to themselves, what the Egyptians were actually doing was defining the Earth's orbital position around the Sun using the seasonal appearance of a star as a gauge and the number of rotations that fit inside an orbital circuit, in this case 1461 rotations for 4 orbital circuits which breaks down into 365 1/4 rotations to one orbital circuit.

This is the founding principle where one 24 hour day keeps in step with one rotation of the Earth and the basis of the Lat/Long system along with the reason why the extra day and rotation is introduced in order to keep the Earth's position in space fixed by the number of rotations,at least to the nearest rotation.

The next step is the process which equates the 'average' 24 hour day with 'constant' rotation insofar as the average 24 hour day substitutes for constant rotation through 360 degrees in that period.






I am reacquainting myself with celestial mechanics as I am playing
with my new sextant.


I've thought about buying the Davis 25 plastic sextant to play with. one practical use would be to confirm the height of the huge Linden trees that border my back yard.
I did a google search and found a link that described how you could estimate height with an upside down protractor, a string with a weighted object as a kind of plumb bob and a ruler to sight along.The ruler would sit on the upside down base of the protractor and the string would give you the sighted angle. The guy provided the formula to get a fairly accurate height.


You haven't mastered left, right, up, and down yet. You aren't ready for
a sextant yet.

--


I don't need anger management. I just need people to stop ****ing me off!
Respectfully submitted by Justan

Principle of the Lat/Long system
 

True North wrote:
On Saturday, 3 January 2015 13:36:04 UTC-4, wrote:
On Sat, 3 Jan 2015 08:14:26 -0800 (PST),
wrote:

This is the broadest possible overview for those who are unfamiliar
with how the motions of the Earth fit in with human timekeeping and
although it is an injustice to those people who created the system we
use today, the overview is much better than none at all. There is no
stopping to differentiate between the original geocentric astronomers
and their observations from the later heliocentric astronomers who
worked off the idea that the Earth moves between Venus and Mars around
the Sun so readers today don't concern themselves with the level of
knowledge of any given era as this will be taken for granted in order
to move the story along.

As the Earth moves through space in its circuit around the Sun,certain
stars lying on or near the same plane as the Earth's orbital motion are
temporarily lost behind the Sun's glare. The older astronomers marked
the passage as the Sun through the constellations (hence birth signs)
but for purposes of this story it is better to consider the apparent
motion of the stars behind the Sun due to the orbital motion of the Earth -

https://www.youtube.com/watch?vîQwYrfmvoQ

The anchor for the Lat/Long system originally was based on the
appearance of one particular star as the orbital motion of the Earth
placed the star just far enough to one side of the Sun one morning,
That star was the brightest one in the celestial arena known as Sirius
and can be seen on the bottom left of the image -

https://www.youtube.com/watch?vîQwYrfmvoQ

".. on account of the procession of the rising of Sirius by one day in
the course of 4 years,.. therefore it shall be, that the year of 360
days and the 5 days added to their end, so one day shall be from this
day after every 4 years added to the 5 epagomenae before the new year"
Canopus Decree 238 BC

Unbeknownst to themselves, what the Egyptians were actually doing was
defining the Earth's orbital position around the Sun using the seasonal
appearance of a star as a gauge and the number of rotations that fit
inside an orbital circuit, in this case 1461 rotations for 4 orbital
circuits which breaks down into 365 1/4 rotations to one orbital circuit.

This is the founding principle where one 24 hour day keeps in step with
one rotation of the Earth and the basis of the Lat/Long system along
with the reason why the extra day and rotation is introduced in order
to keep the Earth's position in space fixed by the number of
rotations,at least to the nearest rotation.

The next step is the process which equates the 'average' 24 hour day
with 'constant' rotation insofar as the average 24 hour day substitutes
for constant rotation through 360 degrees in that period.






I am reacquainting myself with celestial mechanics as I am playing
with my new sextant.


I've thought about buying the Davis 25 plastic sextant to play with. one
practical use would be to confirm the height of the huge Linden trees
that border my back yard.
I did a google search and found a link that described how you could
estimate height with an upside down protractor, a string with a weighted
object as a kind of plumb bob and a ruler to sight along.The ruler would
sit on the upside down base of the protractor and the string would give
you the sighted angle. The guy provided the formula to get a fairly accurate height.

Basic geometry.

Principle of the Lat/Long system
 

On 1/8/2015 12:13 PM, Justan Olphart wrote:
On 1/8/2015 11:05 AM, True North wrote:
On Saturday, 3 January 2015 13:36:04 UTC-4, wrote:
On Sat, 3 Jan 2015 08:14:26 -0800 (PST),
wrote:

This is the broadest possible overview for those who are unfamiliar
with how the motions of the Earth fit in with human timekeeping and
although it is an injustice to those people who created the system
we use today, the overview is much better than none at all. There is
no stopping to differentiate between the original geocentric
astronomers and their observations from the later heliocentric
astronomers who worked off the idea that the Earth moves between
Venus and Mars around the Sun so readers today don't concern
themselves with the level of knowledge of any given era as this will
be taken for granted in order to move the story along.

As the Earth moves through space in its circuit around the
Sun,certain stars lying on or near the same plane as the Earth's
orbital motion are temporarily lost behind the Sun's glare. The
older astronomers marked the passage as the Sun through the
constellations (hence birth signs) but for purposes of this story it
is better to consider the apparent motion of the stars behind the
Sun due to the orbital motion of the Earth -

https://www.youtube.com/watch?v=eeQwYrfmvoQ

The anchor for the Lat/Long system originally was based on the
appearance of one particular star as the orbital motion of the Earth
placed the star just far enough to one side of the Sun one morning,
That star was the brightest one in the celestial arena known as
Sirius and can be seen on the bottom left of the image -

https://www.youtube.com/watch?v=eeQwYrfmvoQ

".. on account of the procession of the rising of Sirius by one day
in the course of 4 years,.. therefore it shall be, that the year of
360 days and the 5 days added to their end, so one day shall be from
this day after every 4 years added to the 5 epagomenae before the
new year" Canopus Decree 238 BC

Unbeknownst to themselves, what the Egyptians were actually doing
was defining the Earth's orbital position around the Sun using the
seasonal appearance of a star as a gauge and the number of rotations
that fit inside an orbital circuit, in this case 1461 rotations for
4 orbital circuits which breaks down into 365 1/4 rotations to one
orbital circuit.

This is the founding principle where one 24 hour day keeps in step
with one rotation of the Earth and the basis of the Lat/Long system
along with the reason why the extra day and rotation is introduced
in order to keep the Earth's position in space fixed by the number
of rotations,at least to the nearest rotation.

The next step is the process which equates the 'average' 24 hour day
with 'constant' rotation insofar as the average 24 hour day
substitutes for constant rotation through 360 degrees in that period.






I am reacquainting myself with celestial mechanics as I am playing
with my new sextant.


I've thought about buying the Davis 25 plastic sextant to play with.
one practical use would be to confirm the height of the huge Linden
trees that border my back yard.
I did a google search and found a link that described how you could
estimate height with an upside down protractor, a string with a
weighted object as a kind of plumb bob and a ruler to sight along.The
ruler would sit on the upside down base of the protractor and the
string would give you the sighted angle. The guy provided the formula
to get a fairly accurate height.


You haven't mastered left, right, up, and down yet. You aren't ready for
a sextant yet.


In the cub scouts we learned to use a ruler held at arms length and a
bit of math to get the height of a tree or anything really.

Principle of the Lat/Long system
 

On Thu, 8 Jan 2015 08:05:52 -0800 (PST), True North
wrote:

On Saturday, 3 January 2015 13:36:04 UTC-4, wrote:
On Sat, 3 Jan 2015 08:14:26 -0800 (PST),
wrote:

This is the broadest possible overview for those who are unfamiliar with how the motions of the Earth fit in with human timekeeping and although it is an injustice to those people who created the system we use today, the overview is much better than none at all. There is no stopping to differentiate between the original geocentric astronomers and their observations from the later heliocentric astronomers who worked off the idea that the Earth moves between Venus and Mars around the Sun so readers today don't concern themselves with the level of knowledge of any given era as this will be taken for granted in order to move the story along.

As the Earth moves through space in its circuit around the Sun,certain stars lying on or near the same plane as the Earth's orbital motion are temporarily lost behind the Sun's glare. The older astronomers marked the passage as the Sun through the constellations (hence birth signs) but for purposes of this story it is better to consider the apparent motion of the stars behind the Sun due to the orbital motion of the Earth -

https://www.youtube.com/watch?v=eeQwYrfmvoQ

The anchor for the Lat/Long system originally was based on the appearance of one particular star as the orbital motion of the Earth placed the star just far enough to one side of the Sun one morning, That star was the brightest one in the celestial arena known as Sirius and can be seen on the bottom left of the image -

https://www.youtube.com/watch?v=eeQwYrfmvoQ

".. on account of the procession of the rising of Sirius by one day in the course of 4 years,.. therefore it shall be, that the year of 360 days and the 5 days added to their end, so one day shall be from this day after every 4 years added to the 5 epagomenae before the new year" Canopus Decree 238 BC

Unbeknownst to themselves, what the Egyptians were actually doing was defining the Earth's orbital position around the Sun using the seasonal appearance of a star as a gauge and the number of rotations that fit inside an orbital circuit, in this case 1461 rotations for 4 orbital circuits which breaks down into 365 1/4 rotations to one orbital circuit.

This is the founding principle where one 24 hour day keeps in step with one rotation of the Earth and the basis of the Lat/Long system along with the reason why the extra day and rotation is introduced in order to keep the Earth's position in space fixed by the number of rotations,at least to the nearest rotation.

The next step is the process which equates the 'average' 24 hour day with 'constant' rotation insofar as the average 24 hour day substitutes for constant rotation through 360 degrees in that period.






I am reacquainting myself with celestial mechanics as I am playing
with my new sextant.


I've thought about buying the Davis 25 plastic sextant to play with. one practical use would be to confirm the height of the huge Linden trees that border my back yard.
I did a google search and found a link that described how you could estimate height with an upside down protractor, a string with a weighted object as a kind of plumb bob and a ruler to sight along.The ruler would sit on the upside down base of the protractor and the string would give you the sighted angle. The guy provided the formula to get a fairly accurate height.

Here, I just saved you a lot of money.

http://forestry.usu.edu/htm/kids-and...ht-measurement

Principle of the Lat/Long system
 

On 1/8/2015 2:19 PM, wrote:
On Thu, 08 Jan 2015 12:24:14 -0500, KC wrote:

On 1/8/2015 12:13 PM, Justan Olphart wrote:
On 1/8/2015 11:05 AM, True North wrote:

I've thought about buying the Davis 25 plastic sextant to play with.
one practical use would be to confirm the height of the huge Linden
trees that border my back yard.
I did a google search and found a link that described how you could
estimate height with an upside down protractor, a string with a
weighted object as a kind of plumb bob and a ruler to sight along.The
ruler would sit on the upside down base of the protractor and the
string would give you the sighted angle. The guy provided the formula
to get a fairly accurate height.


You haven't mastered left, right, up, and down yet. You aren't ready for
a sextant yet.


In the cub scouts we learned to use a ruler held at arms length and a
bit of math to get the height of a tree or anything really.

There are a number of fairly simple geometry tricks to do things like
this. If you have the luxury of choosing your place to shoot the
angle, just use a regular 45 degree drafting triangle and a spirit
level.


Like I said, a 12 inch ruler or a plain old yard stick and your arm..
you need to know the length of your ruler from your eye, and the
distance to the *tree*.. No drafting triangle necessary at all :)

Principle of the Lat/Long system
 

On 1/8/2015 8:48 PM, wrote:
On Thu, 08 Jan 2015 15:16:28 -0500, KC wrote:

On 1/8/2015 2:19 PM, wrote:
On Thu, 08 Jan 2015 12:24:14 -0500, KC wrote:

On 1/8/2015 12:13 PM, Justan Olphart wrote:
On 1/8/2015 11:05 AM, True North wrote:

I've thought about buying the Davis 25 plastic sextant to play with.
one practical use would be to confirm the height of the huge Linden
trees that border my back yard.
I did a google search and found a link that described how you could
estimate height with an upside down protractor, a string with a
weighted object as a kind of plumb bob and a ruler to sight along.The
ruler would sit on the upside down base of the protractor and the
string would give you the sighted angle. The guy provided the formula
to get a fairly accurate height.


You haven't mastered left, right, up, and down yet. You aren't ready for
a sextant yet.


In the cub scouts we learned to use a ruler held at arms length and a
bit of math to get the height of a tree or anything really.

There are a number of fairly simple geometry tricks to do things like
this. If you have the luxury of choosing your place to shoot the
angle, just use a regular 45 degree drafting triangle and a spirit
level.


Like I said, a 12 inch ruler or a plain old yard stick and your arm..
you need to know the length of your ruler from your eye, and the
distance to the *tree*.. No drafting triangle necessary at all :)

Just trying to remove the math for people who think trig is hard.


I forgot, we got lib arts students here... :)