NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: leap seconds a navigational hazard, says expert
From: Brooke Clarke
Date: 2003 Aug 9, 13:37 -0700
From: Brooke Clarke
Date: 2003 Aug 9, 13:37 -0700
Hi Richard:
There are a lot of ways of making heliochronometers. For many years sundials were sued to set watches and clocks. These typically were in the form of noon marks. You mount a disk with a hole in the center and when the Sun crosses a figure eight line at the current date set your watch.
I made one of these by placing a metal plate at the lower end of a South facing skylight and using a 3x5 card with a number of concentric ellipses and a small hole at their center. I just tracked the Sun's image with the card and at exactly noon stopped and drive a small brad nail into the hardwood floor. After many years there would be more than one nail for the same date because as we go through the 4 years of the leap year cycle the timing is a little different.
For more on this and other precision sundials see:
http://www.pacificsites.com/~brooke/Sundial.shtml
http://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=heliochronometers
Have Fun,
Brooke Clarke
Richard M. Pisko wrote:
There are a lot of ways of making heliochronometers. For many years sundials were sued to set watches and clocks. These typically were in the form of noon marks. You mount a disk with a hole in the center and when the Sun crosses a figure eight line at the current date set your watch.
I made one of these by placing a metal plate at the lower end of a South facing skylight and using a 3x5 card with a number of concentric ellipses and a small hole at their center. I just tracked the Sun's image with the card and at exactly noon stopped and drive a small brad nail into the hardwood floor. After many years there would be more than one nail for the same date because as we go through the 4 years of the leap year cycle the timing is a little different.
For more on this and other precision sundials see:
http://www.pacificsites.com/~brooke/Sundial.shtml
http://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=heliochronometers
Have Fun,
Brooke Clarke
Richard M. Pisko wrote:
On Sat, 9 Aug 2003 09:29:56 -0700, Brooke Clarke wrote:There's another problem for me and that's Sundials. There are many dials that are accurate to 15 seconds and changing to a new time format where the time no longer matches the Earth's rotation will make them obsolete.A spot of light in a room? A fixed mirror onto a shaded wall? Please tell me more. And how do you correct for the daily changes? -- Richard ...
