Horology 101

[david pierce]

The science of time is somewhat complex and interesting. Because of their position in the world at that time, England had to rely on the shipping industry for their survival. The shipping industry in turn had to rely on accurate ways of keeping time so it is no accident that the line of longitude starts in Greenwich England.
The time is taken by looking at a distant star through a telescope. The actual time standard is the rotation of the earth which is accurate to one second every 100,000 years. The telescope has a retical with a grid drawn on it marked off in periods of time. As the earth rotates, the star appears to move across the grid, so by counting the grid lines, the astronomer can calculate periods of time. This is called sidereal time and is not particularly useful in this form. This is because the rotation of the earth has no particular relationship to the earth’s rotation around the sun. This has to be averaged out with a statistical mean to be of any pratical use hence the term Greenwich Mean Time. This is how the world time standard was kept until the invention of the Atomic Clock.
When Lewis & Clark surveyed the Louisiana pruchase, they carried a pendulum clock and a telescope. When they wanted to map out a surveying position, they would look through the telescope at one of the major planets (probably Jupiter) and wait for one of its moons to come out from behind the planet. At this point they would release the pendulum which would calibrete their clock. The positions of the moons were recorded on charts they carried so they were able to make accurate position markings.
david

[watchthebear]

Hi all, I believe the earth rotates around it’s axis and revolves around the sun. If I am in error, or lack scientific rigor, please set me right. Stay well……………b

[david pierce]

Bear,
That is true. The problem with telling time is there is no connection between the two. This is why it has to be averaged out statistically. The time you are familar with is called Civil Time or Mean Time. The time recorded with the telescope is called Sidereal Time.
david

[tmac1956]

@david pierce wrote:

The science of time is somewhat complex and interesting. Because of their position in the world at that time, England had to rely on the shipping industry for their survival. The shipping industry in turn had to rely on accurate ways of keeping time so it is no accident that the line of longitude starts in Greenwich England.
The time is taken by looking at a distant star through a telescope. The actual time standard is the rotation of the earth which is accurate to one second every 100,000 years. The telescope has a retical with a grid drawn on it marked off in periods of time. As the earth rotates, the star appears to move across the grid, so by counting the grid lines, the astronomer can calculate periods of time. This is called sidereal time and is not particularly useful in this form. This is because the rotation of the earth has no particular relationship to the earth’s rotation around the sun. This has to be averaged out with a statistical mean to be of any pratical use hence the term Greenwich Mean Time. This is how the world time standard was kept until the invention of the Atomic Clock.
When Lewis & Clark surveyed the Louisiana pruchase, they carried a pendulum clock and a telescope. When they wanted to map out a surveying position, they would look through the telescope at one of the major planets (probably Jupiter) and wait for one of its moons to come out from behind the planet. At this point they would release the pendulum which would calibrete their clock. The positions of the moons were recorded on charts they carried so they were able to make accurate position markings.
david

daivd:

Years ago I took a basic course in surveying in which we dealt with sidereal time and some ofthe celestial time calculations. I often find it interesting that the Western Church still uses these these to set the date of Easter – well, they use algorithims derived from celestial movements something like this:

Easter occurs on the first Sunday after the first full moon after the Vernal Equinox.

It good until the planets get out of alignment to suit the algorithm… < 4100 ad!

Later,
tmac

[watchthebear]

Hello all, I am unsure what this all amounts to; so, a question or two. This is Horology 101. This has, I assume, as it’s prerequisite Hor. 1A and Hor. 1B, making it a very advanced course. Is this correct? If not, Does Hor. 101 propose to be the basic “starter-course” for potential watch repairers and watch makers? If so, what’s the point? I have yet to see, hear, or read any competent or expert watchmaker bemoan the fact that they work hard on instruments that don’t keep real time. So, that is my question: what is the practical purpose of having a working knowledge of Hor. 101? Good health, folks…………………….b

[willofiam]

well, first of all b, I learned the earth is not flat and goes around the sun instead of the sun going around the earth, basically you might say we as humans have been trying for thousands of years to figure out the best way to keep time when really we have no idea of the true concept and origin, we do our best to function in this fallen world, uuuhhh ooohhh 😯 I am LATE for super!!!! William
p.s. interesting point brought up though, I rather enjoy the history and science behind the things we do do.

[david pierce]

Bear,
The point you brought up is a good one which if I understand what you meant is, what does horology have to do with watches and other time keeping machines. The best way I know how to answer it is, a watch is a machine and the watchmaker is a technicion who’s job is to keep the machine functioning properly. Functioning properly means that the watch must move acording to a predetermined standard. Horology is the field that determines that standard. For a watch to actually be a watch it must move in synchronization to that standard within a tolerance. If it does not it is simply a machine and not a functioning watch.
david

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