NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Burdwood's Tables
From: Peter Fogg
Date: 2007 Oct 10, 13:17 +1000
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From: Peter Fogg
Date: 2007 Oct 10, 13:17 +1000
On 10/10/07, John Cole <jfcole@tokopah.com> wrote:
Here's a page from Burdwood's Tables. The latitude limit is 64 degs in the second edition. Commander John Burdwood RN was was in the Admiralty Hydrographic Department. The second edition 1940 was revised by Percy Davis FRAS of HM Nautical Almanac Office.
Thanks for that sample, John. On these Burdwood's Tables and their use:
Captain Burdwood produced a book of tables that allow you to work out the bearing by the declination of the sun (how high it is) on a certain date, a certain time, viewed from a certain latitude. But first! You need to know the 'hour angle' of the sun, which fixes the base of the calculation. You ring up the Duty Officer at the Royal Observatory and he tells you. That's his job. Haven't done it for nearly thirty years now – 'twas fun!
*
They were building some big antennas for the oil rigs. The contractors were set, and ready to pour concrete – millions of pounds of contract were rolling. They were sixty foot 'billboard' antennas – great sheets of curved metal in the sky. The theory was, you pointed it where the oil rigs were and blasted a signal. They were too far away over the curve of the earth, so the signal shot over their heads, but a bit scattered down from the sky and they could communicate. BUT, if you were off the horizontal bearing, you were buggered.
'John?' It wasn't my department. But I had become the 'Burdwood-meister'
'Will you just go up and do an independent check on the bearing? I'll buy you a pint.'
Anyway, so I say to this contractor's bloke. 'Five degrees EAST?' I'd calculated and re-calculated. I had some bad news. He'd done it from a map, from local landmarks. I'd done it from the sun – slightly less accurate, but still: 'Sorry mate. I get about five degrees WEST'
Months later, after they'd re-aligned the antennas, they poured the concrete. I got quite a lot more than a pint in thanks.
*
They were building some big antennas for the oil rigs. The contractors were set, and ready to pour concrete – millions of pounds of contract were rolling. They were sixty foot 'billboard' antennas – great sheets of curved metal in the sky. The theory was, you pointed it where the oil rigs were and blasted a signal. They were too far away over the curve of the earth, so the signal shot over their heads, but a bit scattered down from the sky and they could communicate. BUT, if you were off the horizontal bearing, you were buggered.
'John?' It wasn't my department. But I had become the 'Burdwood-meister'
'Will you just go up and do an independent check on the bearing? I'll buy you a pint.'
Anyway, so I say to this contractor's bloke. 'Five degrees EAST?' I'd calculated and re-calculated. I had some bad news. He'd done it from a map, from local landmarks. I'd done it from the sun – slightly less accurate, but still: 'Sorry mate. I get about five degrees WEST'
Months later, after they'd re-aligned the antennas, they poured the concrete. I got quite a lot more than a pint in thanks.
From:
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To post to this group, send email to NavList@fer3.com
To , send email to NavList-@fer3.com
-~----------~----~----~----~------~----~------~--~---
