The Lunar Distance method was not practical, but it was supported by the
astronomers who felt that a mechanical contraption was beneath the art. Even
Newton, who was the first head of the Longitude Board, would not consider
the use of a mechanical clock. One argument from the astronomers was that
astronomy could determine time but a clock could only keep time.
John WA4WDL
--------------------------------------------------
From: "Chris Albertson" <[email protected]>
Sent: Tuesday, January 24, 2012 1:26 PM
To: "Discussion of precise time and frequency measurement"
<[email protected]>
Subject: Re: [time-nuts] establishing your position w/o gps
have you ever tried to measure an angular distance using a hand held
instrument while standing on the deck of a moving boat in the open
ocean? try it and you will see why they wanted a clock. You
really can't measure an arc minute reliably we should expect about 15
arc minute accuracy if you are standing on a moving ship. A few very
skilled people could do better.
The moon moves what? about 10 degrees per day so in practical terms
you can get time to about 30 minutes. But other sources of error
would add to that. But still knowing even the hour is very good
that puts you in the correct time zone
On Tue, Jan 24, 2012 at 9:54 AM, jmfranke <[email protected]> wrote:
In addition to the moons of Jupiter, there was a method in direct
competition with Harrison. It was the Lunar distance method. The Lunar
distance method used the position of the Earth's moon against the zodiac
as
a clock. The term lunar distance was used because the navigator measured
the
angular distance from the moon to various stars to establish the moon's
position and then the time was deduced from lunar position tables.
Developing the lunar distance tables was part of the reason for
establishing
the Royal Observatory.
John WA4WDL
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