Pub. 229, Sight Reduction Tables for Marine Navigation, solves the same triangle as Pub. 249, more precisely: Hc to 0.1′ and Z to 0.1°, for every declination from 0° to 90°. It is entered with the same assumed position: a whole degree of latitude and of LHA.

Take the volume for your AP latitude: six volumes of 15° each (Volume 3 is 30°–45°).
Turn to the page for your LHA. Each page is one LHA (with 360° − LHA), latitudes across the top, declinations down the side.
Use the same name or contrary name part of the page, as with 249, and the column for your AP latitude.
Go down to the row for the whole degree of declination below the body’s. Read Hc, d and Z.
The declination increment is the rest of the declination: its minutes and tenths.
The Interpolation Table (inside the covers) gives the correction in two parts: the block for your increment, then the line for the tens of d, and the line for its units and tenths. Add them, and give the total the sign of d. It is d × increment ÷ 60.
Zn by the same rules as Pub. 249, printed on every page. Keep the tenth.

Bowditch’s example: Spica, AP latitude N 39°, Dec S 11°08.4′ (contrary name), LHA 329°.

Volume 3, page for LHA 31°/329°, contrary name, latitude 39°, declination 11°: Hc 32°15.9', d −53.0, Z 143.3°.

Increment 8.4′. Interpolation Table: tens of d (50′) give 7.0′; units and tenths (3.0′) give 0.4′. Total −7.4′, the sign of d.

Hc = 32°15.9' − 7.4′ = 32°08.5'.

N. latitude, LHA over 180°: Zn = Z = 143.3°.

Where the altitude changes unevenly with declination (high altitudes, mostly), d is printed in italics with a small dot, and a double second difference correction is added too, from a column of the same table. It is small, usually a few tenths of a minute. The practice here avoids those entries; the book’s introduction explains the method.

Find the example in the page below, then the Interpolation Table.

LatitudeLHA (page)

Go to declination

Volume 3 (30°–45°). The page for LHA 31° (and 329°): latitude contrary name to declination. Hc to 0.1′, d to 0.1′, Z to 0.1°. A d in italics with a dot needs a double second difference.

Dec	39°			40°
Dec	Hc	d	Z	Hc	d	Z
0	41°46.2′	−50.8	136.3	41°02.6′	−51.3	136.9
1	40°55.4′	−51.0	137.0	40°11.3′	−51.5	137.6
2	40°04.4′	−51.2	137.7	39°19.8′	−51.7	138.3
3	39°13.2′	−51.5	138.4	38°28.1′	−51.9	138.9
4	38°21.7′	−51.7	139.1	37°36.2′	−52.1	139.6
5	37°30.0′	−51.9	139.7	36°44.1′	−52.4	140.2
6	36°38.1′	−52.1	140.3	35°51.7′	−52.4	140.8
7	35°46.0′	−52.3	140.9	34°59.3′	−52.7	141.4
8	34°53.7′	−52.4	141.6	34°06.6′	−52.8	142.0
9	34°01.3′	−52.7	142.1	33°13.8′	−53.0	142.5
10	33°08.6′	−52.7	142.7	32°20.8′	−53.2	143.1
11	32°15.9′	−53.0	143.3	31°27.6′	−53.2	143.7
12	31°22.9′	−53.0	143.8	30°34.4′	−53.4	144.2
13	30°29.9′	−53.2	144.4	29°41.0′	−53.5	144.7
14	29°36.7′	−53.4	144.9	28°47.5′	−53.7	145.2
15	28°43.3′	−53.4	145.4	27°53.8′	−53.7	145.7
16	27°49.9′	−53.6	146.0	27°00.1′	−53.9	146.2
17	26°56.3′	−53.6	146.5	26°06.2′	−53.9	146.7
18	26°02.7′	−53.8	147.0	25°12.3′	−54.0	147.2
19	25°08.9′	−53.9	147.5	24°18.3′	−54.2	147.7
20	24°15.0′	−53.9	147.9	23°24.1′	−54.2	148.2
21	23°21.1′	−54.0	148.4	22°29.9′	−54.3	148.6
22	22°27.1′	−54.2	148.9	21°35.6′	−54.3	149.1
23	21°32.9′	−54.2	149.4	20°41.3′	−54.5	149.6
24	20°38.7′	−54.2	149.8	19°46.8′	−54.5	150.0
25	19°44.5′	−54.4	150.3	18°52.3′	−54.6	150.4
26	18°50.1′	−54.4	150.7	17°57.7′	−54.6	150.9
27	17°55.7′	−54.4	151.2	17°03.1′	−54.7	151.3
28	17°01.3′	−54.6	151.6	16°08.4′	−54.7	151.7
29	16°06.7′	−54.5	152.0	15°13.7′	−54.8	152.2
30	15°12.2′	−54.6	152.5	14°18.9′	−54.8	152.6
31	14°17.6′	−54.7	152.9	13°24.1′	−54.8	153.0
32	13°22.9′	−54.7	153.3	12°29.3′	−55.0	153.4
33	12°28.2′	−54.8	153.7	11°34.3′	−54.9	153.8
34	11°33.4′	−54.7	154.2	10°39.4′	−55.0	154.2
35	10°38.7′	−54.9	154.6	9°44.4′	−55.0	154.7
36	9°43.8′	−54.8	155.0	8°49.4′	−55.0	155.1
37	8°49.0′	−54.9	155.4	7°54.4′	−55.0	155.5
38	7°54.1′	−54.9	155.8	6°59.4′	−55.1	155.9
39	6°59.2′	−54.9	156.2	6°04.3′	−55.1	156.3
40	6°04.3′	−54.9	156.6	5°09.2′	−55.1	156.7
41	5°09.4′	−55.0	157.0	4°14.1′	−55.1	157.1
42	4°14.4′	−54.9	157.4	3°19.0′	−55.1	157.5
43	3°19.5′	−55.0	157.8	2°23.9′	−55.1	157.9
44	2°24.5′	−55.0	158.2	1°28.8′	−55.2	158.2
45	1°29.5′	−55.0	158.6	0°33.6′	−55.1	158.6
46	0°34.5′	−54.9	159.0	−0°21.5′	−55.1	159.0
47	−0°20.4′	−55.0	159.4	−1°16.6′	−55.1	159.4
48	−1°15.4′	−55.0	159.8	−2°11.7′	−55.2	159.8
49	−2°10.4′	−55.0	160.2	−3°06.9′	−55.1	160.2
50	−3°05.4′	−54.9	160.6	−4°02.0′	−55.1	160.6
51	−4°00.3′	−55.0	161.0	−4°57.1′	−55.1	161.0
52	−4°55.3′	−54.9	161.4

N. Lat.: LHA over 180°, Zn = Z; under 180°, Zn = 360° − Z. S. Lat.: LHA over 180°, Zn = 180° − Z; under 180°, Zn = 180° + Z.

Interpolation Table

Dec. increment (′)

Increment 8.4′. Tens of d:
10′	20′	30′	40′	50′
1.4	2.8	4.2	5.6	7.0

Units and tenths of d: the row for the units, the column for the tenths.
d	.0	.1	.2	.3	.4	.5	.6	.7	.8	.9
0′	0.0	0.0	0.0	0.0	0.1	0.1	0.1	0.1	0.1	0.1
1′	0.1	0.2	0.2	0.2	0.2	0.2	0.2	0.2	0.3	0.3
2′	0.3	0.3	0.3	0.3	0.3	0.4	0.4	0.4	0.4	0.4
3′	0.4	0.4	0.4	0.5	0.5	0.5	0.5	0.5	0.5	0.5
4′	0.6	0.6	0.6	0.6	0.6	0.6	0.6	0.7	0.7	0.7
5′	0.7	0.7	0.7	0.7	0.8	0.8	0.8	0.8	0.8	0.8
6′	0.8	0.9	0.9	0.9	0.9	0.9	0.9	0.9	1.0	1.0
7′	1.0	1.0	1.0	1.0	1.0	1.1	1.1	1.1	1.1	1.1
8′	1.1	1.1	1.1	1.2	1.2	1.2	1.2	1.2	1.2	1.2
9′	1.3	1.3	1.3	1.3	1.3	1.3	1.3	1.4	1.4	1.4

Correction = tens part + units part, with the sign of d. The same as d × increment ÷ 60.

Reading Pub. 229

Interpolation Table