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Subject: HO 211 vs. Bayless
From: Paul Hirose (71202.2014@XXX.XXX)
Date: Sun Jul 04 1999 - 12:08:26 EDT
Joe Shields mentioned the version of HO 211 by Bayless. I bought that
book, but still prefer the table in Bowditch Vol 2 (which I assume is
identical to the original HO 211), at least at a desk at home.
The main advantage is the consistent arrangement of the A and B
columns. HO 211 always puts B in the right-hand column. Also, the
numbers in the B column are boldface, at least in the Bowditch
reprint. Bayless is less Murphy-resistant. B can be in either
column; you have to look at the heading. It's clearly marked, but you
do need to keep your wits about you, more so than with Ageton.
HO 211 is able to keep the A and B columns always in the same places
because it goes out to 90 degrees on the top column headings before
"turning around". However, the behavior of trig functions is such
that the first and second halves of the table are mirror images.
E.g., A of 10 deg = B of 80 deg. Bayless takes advantage of this by
only going to 45 degrees before turning around. It cuts half the size
off the table, but also forces A and B columns to swap places.
I'm sure Ageton was aware of the redundancy in his table, but accepted
it in the interest of reliability. After all, it only costs 18 more
pages.
Another complaint is that Bayless likes to omit leading digits, if
they're identical for several entries in a row:
Ageton Bayless
163322 163322
162738 2738
162250 2250
Perhaps I just have a mental block, but the Bayless format is
slower for me to absorb.
One practical matter is that Bowditch vol. 2 is a large book and lies
open to any page in the table. Bayless is a small paperback and tends
to flip closed if you let go of it. (However, a 1940s-vintage HO 211
for air navigation owned by a friend has the same problem.)
For negative altitudes, the rules in Bayless are incorrect.
I must say there are some good points to Bayless. Tabulating only
whole minutes simplifies the Bayless table. Each column contains
one complete degree. On the other hand, Ageton only covers a half
degree per column, since 120 entries won't fit. If you want to
look up, say, 16 deg 48 min, find the 18' row in the 16 deg 30'
column. Not hard, but I've managed to botch it.
The Bayless table has a clean, uncluttered look compared with the many
unneccessary dividing lines in Bowditch.
Neither table does a good job indicating the left-hand minutes column
goes with the top column headings and vice versa on the bottom,
though.
Bayless does include a method, devised by guru D.H. Sadler (of the
Royal Observatory, I believe) for solving sights when LHA is near 90
or 270. HO 211 becomes very inaccurate in such circumstances.
The Bayless table only has 1/4 the number of pages as HO 211.
Mike Pepperday's S-Table is yet another Ageton variant. Like Bayless,
he eliminates redundancy by turning the table around at 45 degrees.
His main improvement is to number the table all the way to 360
degrees. You can enter his table with LHA directly, instead of having
to convert to meridian angle if LHA is more than 180. Additional
hand-written column headings would let you do this with the other HO
211 variants, of course.
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