Next message: Frank Reed: "Lunars & Bowditch's First Method"
A few days ago, George H wrote:
"To me, Mendoza's appears to be a remarkably complex and long-winded method,
even though it avoided the necessity for using long 5-figure or 6-figure
logarithm tables."
My first impression was similar, but I've since tried it and it's really not
much more work than, say, Witchell's method (which would have been its chief
competitor). It has one ENORMOUS advantage over some other methods. It does not
suffer from "an embarassment of cases", as they used to say. And this is
important in a practical method. If you accidentally mis-apply one of the "if -
then" rules which are common in so many lunar methods, you have to re-do a large
part of the calculation. A calculational method with a linear unbranching
path through its steps has advantages
And the Mendoza Rios method was popular for a very long time --most of the
period when lunars flourished. It was one of only two methods in Moore c.1800
(the other being Witchell's) and it was included in most of the standard
navigation manuals (Bowditch, Norie) up through 1850 at least when lunars were in
rapid decline.
Also the rather famous First Method of Bowditch is really a very slight
variation on the method of Mendoza Rios (MR's method was published in 1796).
Bowditch combined a few repetitive calculations from MR's method into special
tables. For example, adding that "constant logarithm" 9.6990 is a waste of time in
the standard MR method, and (if I am remembering correctly) Bowditch prepared a
special table with that constant log folded into the main table. In my
opinion, Bowditch's importance to nautical astronomy and nautical mathematics is
more legend than fact. Mendoza Rios deserves to be better known. I think I'll
work on that...
Frank R
[ ] Mystic, Connecticut
[X] Chicago, Illinois
