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Re: HO 211 Sadler Technique
From: Paul Hirose
Date: 2014 Mar 09, 13:45 -0700
From: Paul Hirose
Date: 2014 Mar 09, 13:45 -0700
"Compact Sight Reduction Table" by Allan E. Bayless, a modified HO 211, shows the Sadler technique with this example: 89° 06′ t B 180390 A 5 53° 16′ S dec A 9614 +B 22323 +B 22323 33° 19′ S lat +A 26022 +B 7798 ----- 26° 07′ h1 A 35636 26° 35′ Ho ------- 52° 42′ h1+Ho 26° 21′ (h1+Ho)/2 -B 4764 ------ 0° 30′ h2 A 205747 ------- 26° 37′ hc = h1+h2 -B 4865 ----- 41° 59′ Z A 17463 With a calculator I get Hc = 26° 37.1′ and Z = 41° 59.0′. Speaking of the Bayless table itself, I don't like it as well as the Ageton table in Bowditch vol. 2. (I don't own a "real Ageton".) To cut the table size in half, Bayless goes up to 45° instead of "turning around" at 90°. This is possible because of the symmetry of the trig functions, e.g., sin 80° = cos 10°. Thus the table need only go as high as 45°. However, it requires a double heading at the top and bottom of each column. Depending on the angle, the left hand column can be either the A or B value of the angle. On the other hand, the table in Bowditch always has the A value on the left and B on the right. In addition, the B column is boldface. These things help you avoid blunders. The other thing I don't like about Bayless is that he omits the leading digits when they are the same for several consecutive entries. For example, 33925 901 876 852 827 so you have look in two places to get all the digits. --