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Re: Longitude by Time Sight...good enough at sea?
From: Hanno Ix
Date: 2012 Dec 20, 15:41 -0800
From: Dave Walden <waldendand@yahoo.com>
To: NavList@fer3.com
Sent: Thursday, December 20, 2012 11:51 AM
Subject: [NavList] Re: Longitude by Time Sight...good enough at sea?
From: Hanno Ix
Date: 2012 Dec 20, 15:41 -0800
Question:
As you know it is a simple arithmetic to write his [cos(t/2)]^2- formula (pg15)
in terms of sine, cosine. And since he uses logarithms anyway, there is
effectively no difference at all:
log10(sec(70deg)) = + 0.46595 and log10(cos(70deg)) = - 0.46595.
So, when ignoring the minus sign his table is a log10(cos())
and a log10(sin()) anyway.
He even transfers sin^2 into cosec^2 which complicates things.
Is there a particuler reason why Weems uses cosecants, secants
rather than the more familiar sine, cosine?
h
From: Dave Walden <waldendand@yahoo.com>
To: NavList@fer3.com
Sent: Thursday, December 20, 2012 11:51 AM
Subject: [NavList] Re: Longitude by Time Sight...good enough at sea?
http://www.hathitrust.org/
often a better index than google books own
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