Imágenes de páginas
PDF
EPUB
[blocks in formation]

Ex. 7. 1865, September 23rd. A.M. at ship, latitude 59° 30' N., observed altitude sun's L.L. 10° 50' 10", index correction + 6' 10", height of eye 18 feet, time by chronometer 22d 11h 44m 20s (or 22d 11h 44m 20° P.M.), which was 30m 4s fast for mean noon at Greenwich, August 13th, and losing 10s 5 daily.

[merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small]

EXAMPLES FOR PRACTICE.

Ex. 1. 1865, January 2nd, A.M. at ship, latitude 36° 59' S., observed altitude sun's L.L. 49' 10', index correction - 2′ 40′′, height of eye 14 feet, time by a chronometer id 19h 8m 50s (being 7h 8m 50s A.M. at Greenwich), which was slow 18m 2s for mean noon at Greenwich, November 30th, 1864, and losing 65.8 daily.

Ex. 2. 1865, February 19th, P.M. at ship, latitude 38° 18' S., observed altitude sun's L.L. 21° 30' 40", index correction — 6′ 45′′, height of eye 14 feet, time by a chronometer 18a 19h 53m 37s-6 (being 7h 53m 37s6 A.м, at Greenwich), which was 4m 16s-6 fast for mean noon at Greenwich, January 23rd, and gaining 78.6 daily.

Ex. 3. 1865, March 28th, P.M. at ship, latitude 20° 19' S., observed altitude sun's L.L. 30° 14′, index correction - 2' 10", height of eye 30 feet, time by chronometer 28d oh 10m (being oh 10m P.M. at Greenwich), which was 51m 56s fast for mean noon at Greenwich, December 2nd, 1864, and losing 4s'o daily.

Ex. 4. 1865, April 6th, A.м. at ship, latitude 53°5′ N., observed altitude sun's L.L. 16° 8′ 40′′, index correction 40", height of eye 15 feet, time by a chronometer 5d 19h 18m 49s (being 7b 18m 498 A.M. at Greenwich), which was 2m 38s fast for mean noon at Greenwich, March 11th, and gaining 56 daily.

Ex. 5. 1865, May 1st, P.м. at ship, latitude 21° 8' N., observed altitude sun's L.L. 28° 5′ 30′′, index correction + 2′ 50′′, height of eye 16 feet, time by a chronometer, April 30d 18h 50m 2984 (being 6h 50m 298.4 A.M. at Greenwich), which was 10m 128 slow for mean noon at Greenwich, December 31st, 1864, and gaining 383 daily.

Ex. 6. 1865, June 15th, A.M. at ship, latitude 12° 11' N., observed altitude sun's L.L. 39° 39′ 40′′, index correction + 20°, height of eye 17 feet, time by a chronometer 14d 17h 59m 30s (being 5h 59m 30s A.M. at Greenwich), which was 2m 298.5 slow for mean noon at Greenwich, May 12th, and gaining 9o 4 daily,

Ex. 7. 1865, July 5th, A.м. at ship, latitude 23° 48′ N., observed altitude sun's L.L. 48° 36′ 50′′, index correction - 50′′, height of eye 17 feet, time by a chronometer 5d oh 42m 38s (being oh 42m 38s P.M. at Greenwich), which was 6m 50s fast for mean noon at Greenwich, June 1st, and gaining 457 daily.

Ex. 8. 1865, August 13th, A.м, at ship, latitude 30° 46′ S., observed altitude sun's L.L. 27° 15', index correction - 1' 15", height of eye 21 feet, time by chronometer 13d 2h om (being 2h om P.M. at Greenwich), which was 25m 13s slow for mean noon at Greenwich, May 1st, and gaining 2o6 daily.

Ex. 9. 1865, September 1st, P.M. at ship, latitude 35° 49′ N., observed altitude sun's L.L, 44° 32′ 10′′, index correction + 1′ 46′′, height of eye 20 feet, time by chronometer, August 31d 19h 24m 578 (being 7h 24m 57s A.M. at Greenwich), which was 12m 17s fast for mean noon at Greenwich, July 31st, and gaining 0.7 daily.

Ex, 10.

1865, October 25th, P.M. at ship, latitude 51° 30' S., observed altitude sun's L.L. 40° 22′, index correction 1' 50", eye 20 feet, time by a chronometer 25d 8h 22m 18 (or 8h 22m 1s P.M.) slow 21m 19s on July 20th, and gaining 47 daily.

Ex. 11. 1865, November 27th, A.M. at ship, latitude 39° 20' S., observed altitude sun's L.L. 34° 37′ 55′′, index correction + 1′ 15′′, eye 18 feet, time by a chronometer 27 7h 41m 30s (being P.M. at Greenwich), fast 29m 40s on November 9th, and losing 657 daily.

Ex. 12. 1865, December 25th, A.M. at ship, latitude 9° 59′ S., observed altitude sun's L.L. 10° 38′ 45′′, index correction 3' 12", eye 18 feet, time by a chronometer 24d 15h 29m 50s (being A.M. at Greenwich), slow 38m 59s 5 July 29th, and losing 95.3 daily.

[ocr errors]

Ex. 13. 1865, January 1st, P.M. at ship, latitude 38° 28′ S., observed altitude sun's L.L. 39° o', index correction, 2′ 25′′, eye 12 feet, time by a chronometer Id 11h 58m 29s (being P.M. at Greenwich), slow 1h 52m 53s on October 13th, 1864, and losing 68.9 daily.

Ex. 14. 1865, February 11th, A.M. at ship, latitude 53° 12' N., observed altitude sun's L.L. 12° 10, index correction 49", eye 12 feet, time by a chronometer 10d 22h 22m 228 (being. A.M. at Greenwich), fast 38m 59s on December 1st, 1864, and gaining 8.3 daily,

Ex. 15. 1865, October 26th, A.M. at ship, latitude 28° 10' N., observed altitude sun's U.L. 25° 32′ 20, index correction o', eye 17 feet, time by chronometer oh 54m 6s (being P.M. at Greenwich), fast on September 4th, 30m 6s, losing 2a.5 daily.

Ex. 16. 1865, February 6th, P.м, at ship, latitude 6° 58′ N., observed altitude sun's U.L. 21° 43′ 40′′, index correction o', eye 18 feet, time by chronometer 11h 40m 268 (being A.M at Greenwich), slow 17m 428 on January 20th, and losing 5o4 daily.

[ocr errors]

Ex. 17. 1865, April 21st, P.M. at ship, latitude at noon o° 19' N., observed altitude sun's U.L. 32° 21′ 10′′, index correction 1' 10", eye 12 feet, time by a chronometer 3h 44m 1s (being A.M. at Greenwich), slow 9m 7s on November 14th, 1864, gaining 15.6 daily, course since noon S.W. by W. (true), distance 56 miles: required longitude at time of observation and also at noon.

Ex. 18. 1865, August 21st, A.m. at ship, latitude at noon, o° 20′ S., observed altitude sun's L.L. 33° 49′, index correction + 2′ 10′′, eye 15 feet, time by chronometer 8h 14m os (being P.M. at Greenwich), slow 4m 40o on March 13th, losing 18:25 daily, course S.W. by W., 36 miles.

Ex. 19. 1865, March 20th, A.M. at ship, latitude o°, observed altitude sun's L.L. 28° 50′ 10′′, index correction + 1', eye 23 feet, time by chronometer 20d 2h om (being P.M. at Greenwich), which was fast 2m 8o on Greenwich mean noon, February 28th, and gaining os 3 daily.

Ex. 20. 1865, June 15th, A.M. at ship, latitude 29° 10' S., observed altitude sun's L.L. 30° 40′, eye 25 feet, time by chronometer 14d 10h 59m 20s (being P.M. on 14th at Greenwich), fast 4m 35s on Greenwich mean noon, March 20th, losing 8s daily.

Ex. 21. 1865, March 21st, A.M. at ship, latitude 41° 32' S., observed altitude sun's L.L. 32° 59′, eye 20 feet, time by chronometer 21d 3h 28m (being P.M. at Greenwich), fast 1m 40s on mean time at Greenwich, December 20th, 1864, losing oo9 daily.

VARIATION BY AN AZIMUTH.

Given the latitude, altitude, and declination of an object, to find the true azimuth.

RULE LVII.

1o. Add together the polar distance, the latitude, and the altitude, take half the sum, and take the difference between the half sum and the polar distance.

2o. Add together the log. secant of latitude, the log. secant of altitude, the log. cosines of the half sum and remainder; the sum (rejecting tens) is log. sine square of true azimuth (Table 69, Raper). Or, half the sum of the four logs. is the log. sine of half the true azimuth, which take out of the table (Table 24, Norie), and double it: the result is the true azimuth. 3°. Mark the true azimuth N. when the latitude is S., but mark it S., when the latitude is N.; also, mark it E. when it is A.M., or the altitude is increasing, but W. when it is P.M., or the altitude is decreasing.

(a) When latitude is o, if declination is N., reckon the azimuth from the South; if declination is S., reckon the azimuth from the North.

(b) When both latitude and declination are o, the object moves on the prime vertical, or is E. while the altitude is increasing, and W. while the altitude is decreasing.

Ex. 1.

EXAMPLES.

Given the latitude 47° 46' S.; declination 22° 27′ 22′′ (or polar distance 67° 32′ 38′′); true altitude 26° 44'. (being P.M.)

[merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small]
[merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small]

In each of the following examples it is required to find the true

[merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][ocr errors][merged small][merged small][ocr errors][merged small][ocr errors][merged small][ocr errors][merged small][ocr errors][merged small][merged small][ocr errors][merged small][ocr errors][merged small][ocr errors][merged small][ocr errors][merged small][ocr errors][merged small][ocr errors][merged small][ocr errors][merged small][ocr errors][merged small][ocr errors][merged small][ocr errors][merged small][ocr errors][merged small][ocr errors][merged small][merged small][ocr errors][merged small][ocr errors][merged small][merged small][ocr errors][merged small][merged small][ocr errors][merged small][ocr errors][merged small][ocr errors][merged small][ocr errors][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][ocr errors][merged small][ocr errors][merged small][merged small][merged small][ocr errors][merged small][ocr errors][ocr errors][merged small][ocr errors][ocr errors][merged small][merged small][ocr errors][merged small][merged small][merged small][ocr errors][merged small][merged small][ocr errors][merged small]
« AnteriorContinuar »