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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Proportional logs, etc.
From: Bruce Stark
Date: 2004 Aug 26, 19:39 EDT
From: Bruce Stark
Date: 2004 Aug 26, 19:39 EDT
Henry,
As for how to calculate proportioning logs:
They are for a three hour interval, and designed to proportion to the nearest second of time. Three hours contains 10800 seconds.
One hour contains 3600 seconds. So the PL of one hour is simply the log of 10800/360.
The PL of seven seconds is the log of 10800/7.
The PL of one minute, six seconds is the log of10800/66.
And so on.
Since there are 10800 seconds of arc in three degrees, PL tables can be used to proportion small angles as well.
Hope this helps.
Bruce
As for how to calculate proportioning logs:
They are for a three hour interval, and designed to proportion to the nearest second of time. Three hours contains 10800 seconds.
One hour contains 3600 seconds. So the PL of one hour is simply the log of 10800/360.
The PL of seven seconds is the log of 10800/7.
The PL of one minute, six seconds is the log of10800/66.
And so on.
Since there are 10800 seconds of arc in three degrees, PL tables can be used to proportion small angles as well.
Hope this helps.
Bruce