Ex. 3. 1887, Sept. 23rd, P.M. at ship, lat. acct. 51° 2′ N., long. 41° 13′ E., obs. alt. sun's L.L. South of observer 38° 44′ 20′′, index corr. + 1′ 8′′, height of eye 21 feet, when a chronometer showed Sept. 22d 21h 24m 37', which was 6m 38 fast on Greenwich mean time: required the latitude.

Omitting const. log. the

sum of the other logs. is
arcs we get half
6 620813, which taken out
of log. sins. in Table for
red. +1.26, which multi-
plied by 2 gives Red. +
2' 52" (see foot of p. 268).

Ex. 4. 1887, May 5th, P.M. at ship, latitude account 5° 13' N., longitude 61° E., observed altitude sun's L.L. 78° 41′ N., eye 17 feet, time by watch 5h 1m 7o, which had been found fast on app. time at ship 4h 50m 57o, difference of longitude made since 20 miles West. Green. date, app. time, May 4d 20h 4m 48°.

App. time at ship, May 5d oh 8m48

Hourly diff., 5th noon, 42" 80 X Green. time 3h 92 = 167′′·7760 ÷ 60 = a′ 48′′, decl. noon 5th, 16° 14′ 25′′ N. — 2′ 48′′ red. decl. 16° 11′ 37′′ N.

1. 1887, January 4th, A.M. at ship, latitude by account 36° 47′ N., longitude 27° 12′ W., observed altitude sun's L.L. South of observer was 30° 12′ 10′, index correction + 4′ 19′′, height of eye 28 feet, time by chronometer January 4d 1h 34m 40o, which was 5m 18o slow on Greenwich mean time: required the latitude by reduction to the meridian.

2. 1887, February 28th, P.M. at ship, lat. acct. 43° 46′ N., long. 12° 31′ W., obs. alt. sun's L.L. 38° 1' 15" S., index corr. - 5′ 10′′, height of eye 23 feet, time by chronometer Feb. 28d 1h 16m, which was 2TM 4' slow on mean time at Greenwich: required the latitude by reduction to the meridian.

3. 1887, March 20th, A.M. at ship, lat. 41° 24′ S., long. 105° E., obs. alt. sun's L.L. 47° 46′ N., index corr. + 26′′, eye 22 feet, time by chronometer March 19d 16h 48m, which was 2m 270 fast on mean time at Greenwich: required the latitude by reduction to meridian. 4. 1887, April 21st, A.M. at ship, lat. acot. 39° 54′ N., long. 6o 6′ E., obs. alt. sun's L.L. 61° 26′ 35′′ S., index corr. + 1', eye 18 feet, time by chronometer April 21d oh im 6o, which was 45 220 fast on mean time at Greenwich: required the latitude.

5. 1887, May 29th, P.M. at ship, lat. acct. 37° 15′ S., long. 112° W., obs. alt. sun's L.L. 30° 22′ 30′′ N., index corr. + 49′, eye 22 feet, time by chronometer May 29d 7h 41m, which was 5 23 fast on Greenwich mean time: required the latitude.

6. 1887, June 19th, A.M. at ship, lat. acct. 44° 24′ N., long. 14° 5′ W., obs. alt. sun's L.L 68° 37′ 5′′ South of observer, eye 18 feet, time by chronometer June 19d oh 38m 42", which was 3m 32 slow on mean time at Greenwich: required the latitude by reduction to meridian. 7. 1887, July 16th, A.M. at ship, lat. acct. 0° 38′ S., long. 2° W., obs. alt. sun's L.L. 67° 41′ (zenith S.), eye 15 feet, time by chronometer July 15d 23h 59, which was 9a 5o slow on mean time at Greenwich: required the latitude by reduction to the meridian.

8. 1887, August 30th, P.M. at ship, lat. acct. 41° 15′ N., long. 139° 25′ E, obs. alt. sun's L.L. 57° 20′ S., index corr. + 2′ 21′′, eye 14 feet, time by chronometer Aug. 30d oh 22m 22o, which had been found to be 18o slow of app. time at ship, diff. of long. made to West was 34'.

NN

9.

1887, September 9'h, P.M. at ship, lat. acct. 9° 20′ N., long. 178° 30′ E., obs. alt. sun's L.L. 85° 19' (zen. N.), eye 20 feet, time by watch 11h 59m 40o, slow on app. time at ship 2 40o, diff. of long. made to East was 10.

.

10. 1887, Otober 11th, P.M. at ship, lat. acct. 45° 51′ N., long. 85° 3' E., obs. alt. sun's L L. 36° 38′ 15′′ S., index corr. - 5′ 15′′, eye 16 feet, time by chronometer rod 18h 50m 10o, which was 5h 40m 12o slow on app. time, diff. of long. 33′ W.

II.

1887, November 3rd, P.M. at ship, lat. acct. 32° 16′ S., long. 109° 39′ E., obs. alt. sun's L.L. 71° 50' N., index corr. + 32′′, eye 18 feet, time by watch 2a 22h 22TM, which was found 2h slow, diff. of long. 28'7 West.

12. 1887, December 23rd, A.M. at ship, lat. acct. 47° 22′ S., long. 27° 3′ W., obs. alt. sun's L.L. 65° 10′ 15′′ N., index corr. + 45", eye 12 feet, time by watch 11h 29m 42, found to be 18m 40 slow, diff. of long. was 36' East.

13. 1887, January 5th, P.M. at ship, lat. acct., 8° 50' N., long. 130° 14′ W., obs. alt. sun's L.L. 58° 6' 10" S., eye 21 feet, time by watch oh am 40", found 13 48 slow on app. time, diff. of long. made since 16' East.

14. 1887, April 28th, A.M. at ship, lat. acct. 18° 46′ S., long. 34° 12′ W., obs. alt. sun's L.L. 56° 28′ (zen. S.), index corr. + 1′ 5′′, eye 21 feet, time by watch 11h 49m 50o, found fast 2m 17 on app. time at ship, diff, of long. made since 17 West.

15. 1887, March 21st, A.M. at ship, lat. acct. 19° S., long. 178° 54′ E., obs. alt. sun's L.L. 70° 21' N., index corr. - 2′ 10′′, eye 16 feet, time by watch 8m 17a, found fast on app. time at ship 26m 11o, diff. of long. made since 14 East.

16. 1887, April 12th, A.M. at ship, lat. acct. 0°, long. 164° 12′ W., obs. alt. sun's L.L. 80° 30' N., index corr. · 5′ 10', eye 21 feet, time by watch 12d oh om 2o, fast on app. time at ship 10m 51o, diff. of long. made to East 7.

17. 1887, December 11th, A.M. at ship, lat. acct. 62° 40′ S., long. 100° 10' E., obs. alt. sun's L.L. 50° o' N., index corr. + 2' 10", eye 18 feet, time by watch 10d 17h 2m 46o, which had been found to be 9m 30 fast on mean time at Greenwich: required lat, by reduction to meridian.

18. 1887, July 23rd, A.M. at ship, lat. acct. 68° 25′ N., long. 35° 24′ E., obs. alt. sun's L.L. 40° 58′ S., index corr. o*, eye 17 feet, time by watch oh 21m, found fast on app. time at ship 1h 4m 12o, diff. of long. made since 9'6 East.

19. 1887, March 11th, P.M. at ship, lat. acct. 60° 59′ S., long. 29° 11′ W., obs. alt. sun's L.L. 32° 26′ 50′′ N., index corr.—3′ 0′′, eye 13 feet, time by watch March 114 ob 45 46", found to be 24m 41o fast, diff. of long. was 39′ W.

20. 1887, September 22nd, A.M. at ship, lat. acct. 45° 45′ S., long. 111° 42′ W., obs. alt. sun's L.L. 43° 50' N., index corr. - 5' 40", eye 18 feet, time by watch 22d 7h 41m 10", found to be 8h 4m 10 fast, diff. of long. was 13'5 East.

MERIDIAN ALTITUDE OF A FIXED STAR.

RULE LXXXI.

1o. Take from Nautical Almanac the star's declination.

2°. To the observed altitude apply the index error, as the sign attached directs. 3°. Subtract the dip answering to the height of eye (Table 5, NORIE; Table 30, RAPER).

4°. Subtract the refraction (Table 4, NORIE; Table 31, RAPER), and thus get the true altitude.

5°. Subtract the true altitude from 90°; the remainder is xenith distance.

6°. Mark the zenith distance N. or S., according as the observer is North or South of the star.

7°. Underneath this last place the declination, and take their sum if they have the same names; but take their difference if they have unlike names: the result, in either case, will be the latitude.

The declination of a fixed star changes so slowly that it may be taken out of the Nautical Almanac by inspection, without any practical error resulting; a Greenwich date, therefore, is clearly unnecessary.

8°. When the zenith distance and declination are of the same name, the latitude is of that name; when the zenith distance and declination are of different names, the latitude takes the name of the greater.

Date.

Jan. I

a Andromedæ R.A. Decl. N.

oh 2m

28727'

32**35 64" 5 32.20 635

ET

21

32.06

62.2

The stars are inserted in the Nautical Almanac in the order of their Right Ascension, from ob to 24h; it will, therefore, very much facilitate the finding of the given star in the Nautical Almanać, to turn, in the first instance, to the three pages 289-292, Nautical Almanac, 1887, and seek for the given star under the head "Mean Places of Stars" for January, and thence obtain the star's Right Ascension, which find at the top of one of the pages following 310-365, Nautical Almanac, 1887), which will give the star, and the declination will be found opposite the day in the side column which is nearest the given day. The degrees (°) and minutes (') are placed at the top of the column (as annexed), and the seconds (") are ranged below, for the sake of economizing space in the second column below the name of the star. If the seconds exceed 60", only take the excess of 60", and increase the minutes (') at the top by 1. Thus, on May 11th, 1887 (see table annexed), the declination of a Andromeda is 28° 27′ 50′′ N., and on January 1st the declination is 28° 28′ 5′′ N., 64′′5 being 1′ 5′′, which being added to 28° 27', which stands at the head of the column, gives the declination 28° 28′ 5′′.

23

&c. May 1

3193 60'7 &c.

32°31

&c.

49.8

32.56 50°1

21 32.85

50'7

&c.

&c.

&c.

It may happen that you cannot find the star in the Nautical Almanac under the name given in the question; in that case refer to some other Table of Stars, as Table 13, Norie, where you will find the proper names and constellations. For instance, the star Alphacca is not found under that name in the Nautical Almanac, but in Table 13, NORIE, you will see alongside Alphacca a Corona Borealis, which name you will find in the Nautical Almanac, as before.