Ex. 18. 1872, Sept. 16th, A.M. at ship, lat. acct. 42° 36′ S., long, 137° 10′ E., obs. alt. sun's L.L. 44° 6′ N., index corr. + 2′ 10′′, eye 19 feet, time by watch 16a 8h 41m435, which had been found to be 9h 2m 478 fast on app. time at ship, the diff. of long. made to West was 14' after the error on app. time at ship was determined.

Ex. 19. 1872, March 16th, A.M. at ship, lat. acct. 37° 42′ N., long. 61° 40′ E., obs. alt. sun's L.L. 50° o' 30" S., index corr. +34", eye 15 feet, time by watch 10h 53m 315, found slow on app. time at ship 1h 3m 228, diff. of long. made since 18' West.

Ex. 20. 1872, December 31st, A.M, at ship, lat. acct. 52° N., long. 12° 53′ W., obs. alt. sun's L.L. 14° 46' S., eye 19 feet, time by watch oh 56m, which was fast on app. time at ship 1h 5m 20s, diff. of long. 21'4 West.

Ex. 21. 1872, March 5th, P.M. at ship, lat. acct. 33° 35′ N., long. 78 E., obs. alt. sun's L.L. 49° 53'.15" S., index corr. 3' 15", eye 22 feet, time by watch 4d 19h 2m 129 found to be 5h 17m 12s slow, diff. of long, was 10' E.

Ex. 22.

1872, 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′′, height of eye 18 feet, time by watch 22d 7h 41m 10%, found to be 8h 4m 10s fast, diff. of long. was 13'5 East.

Ex. 23. 1872, December 23rd, P.M. at ship, lat, acct. 42° 16′ N., long. 4° 39′ W., obs. alt. sun's U.L. 24° 14' 10" S., eye 11 feet, time by watch oh 50m 58, fast on app. time at ship 19m 38%, diff. of long. 21'3 West.

MERIDIAN ALTITUDE OF A FIXED STAR.

RULE LXXIV.

1°. 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 the zenith 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.

a Andromedæ.

Date.

R.A.

Decl. N.

oh Im

28° 22'

Jan. I

459'17

62"-8

II

45'04

61.8

21 44'90

60.6

31

44.78

59'2

&c.

&c.

&c.

The stars are inserted in the Nautical Almanac in the order of their Right Ascension, from oh to 24h; it will therefore, very much facilitate the finding of the given star in the Nautical Almanac, to turn, in the first instance, to the three pages (325-328 Nautical Almanac, 1872), and thence obtain the star's Right Ascension, which find at the top of one of the pages following 332-387, Nautical Almanac, 1872), 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 tenth, the declination of a Andromeda is 28° 22′ 49′′ N., and on January 1st, the declination is 28° 23′ 3′′ N., 62"-8 being 1' 3", which being added to 28° 22', which stands at the head of the column, gives the declination,

In each of the following examples it is required to find the latitude:

Correct the courses for variation and leeway, and find the course and distance from the given point, and the latitude and longitude in by inspection.

4. 1872, January 1st, in longitude 102° 41′ W., the observed meridian altitude of sun's L.L. was 59° 59' 50', bearing South, index error +50", height of eye 15 feet: required the latitude.

5. In latitude 37° N., the departure made good was 89.2 miles: required the difference of longitude by parallel sailing.

6. Required the course and distance from Toulon to Valencia by Mercator's

7.

ADDITIONAL FOR ONLY MATE.

1872, January 6th, find the times of high water at Cherbourg, A.M. and P.M." 7a. 1872, January 17th, find A.M. and P.M. tides at A, longitude 50° W., change tide 2h 10m (by Rule LXIV, pages 179 and 180).

7b. 1869, Jan. 6th, find A.M. and P.M. tides at Cherbourg (Admiralty Tide Tables.) 8. 1872, January 1st, at 8h 4m A. M. apparent time at ship, in latitude 50° 32′ N., longitude 139° 51′ W., the sun's magnetic amplitude E. by S. S.: required the true amplitude and variation.

9. 1872, January 29th, P.M. at ship, latitude 42° 26' N., observed altitude sun's L.L. 13° 40', index error 1 14", height of eye 16 feet, time by chronometer 29d 6h 48m 40o, which was 8m 75 slow for Greenwich mean noon, January 1st, and gaining 6-3 daily; required the longitude by chronometer.

THE SAME, AS PROPOSED AT LIVERPOOL :—

1872, January 29th, at about 3h 30m P.M. at ship, latitude 42° 26' N., longitude account 49° 15′ W., observed altitude sun's L.L. 13° 40', index corr. - 1′ 14′′, height of eye 16 feet, when a chronometer showed 6h 48m 40%, which was 8m 75 slow for Greenwich mean noon, January 1st, and gaining 65.3 daily.

ADDITIONAL FOR FIRST MATE.

IO. 1872, January 15th, mean time at ship 9h 39m 44* A.M., latitude 23° 39′ S., longitude 127° 52′ W., sun's magnetic azimuth S. 93° E., observed altitude sun's L.L. 55° 8' 30", index error - 2′ 30′′, height of eye 12 feet: required the true azimuth and variation.

II. 1872, January 17th, P.M. at ship, latitude by account 36° 2' N., longitude 149° 28′ E., observed altitude sun's L.L. South of observer was 32° 54′ 15′′, index error +2' 18', height of eye 22 feet, time by watch 11h 59m, which had been found to be 20m 24s slow on apparent time at ship, the difference of longitude made to the West, since the error of watch on apparent time at ship was determined, was 39'2 required the latitude by reduction to meridian.

ADDITIONAL FOR MASTER ORDINARY.

12. 1872, January 24th, the observed meridian altitude of the star a Tauri (Aldebaran) was 52° 36' bearing South, index correction - 23", height of eye 20 feet: required the latitude.

13. Correct the following compass courses for deviation, as given at page 138:N.N.W., N., and N.E. by N.

EXAMINATION PAPER.-No. II.

FOR SECOND MATE,

1. Multiply 50060 by 800, by common logarithms.

2. Divide 9999'46 by 67.8, by common logarithms.

• Only one method of working Tides is required of candidates-Method I is used at most of the English Ports; at London and Liverpool, Method III, by Admiralty Tide Tables, while at Aberdeen Method II is used.