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Volume 47, 1914
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Art. LV.—The Longitude, Latitude, and Height of the Hector Observatory, Wellington, New Zealand.

[Read before the Wellington Philosophical Society, 28th October, 1914.]

(A.) Longitude.

1. In 1883 the difference of longitude between the Sydney Observatory, Australia, and the Mount Cook Observatory, Wellington,* New Zealand, was determined by means of the electric telegraph. The late Mr. H. C. Russell, Government Astronomer of New South Wales, observed at Sydney, and Mr. C. W. Adams, Geodesical Surveyor, observed at Wellington. The difference of longitude was found to be 1h. 34m. 16.984s. 0.020s.

2. A point 198.38 links due north of the Mount Cook Observatory is the initial point of New Zealand surveys..

3. From this origin, and on the meridian of Mount Cook, the co-ordinates of the Bolton Street Observatory and of the Hector Observatory have been determined by Mr. J. D. Climie, Inspector of Surveys, Lands and Survey Department. These co-ordinates are,—

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North. West.
Links. Links.
Mount Cook initial 0.00 0.00
Bolton Street Observatory, transit instrument 11077.90 2081.94§§
Hector Observatory, transit instrument 8518.50 3535.03

4. From the co-ordinates in 3 the differences of longitude, latitude, and azimuth have been calculated, using Clarke's 1880 Spheroid and Tables of Geodetic Factors,* with the following results:—

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Differences of
Long. Lat. Azi.
s. ' " "
Mount Cook initial–Bolton Street Observatory 1.200 1 12.238 11.875
Mount Cook initial–Hector Observatory 2.037 0 55.550 20.165

[Footnote] * For the information of readers who have no local knowledge of New Zealand, it ought to be stated that the “Mount Cook Observatory” was demolished shortly after the observations were made in 1883, and a gaol built on the site; it was situated on a small knoll in the southern part of Wellington City, and had no connection with “Mount Cook,” the highest mountain in New Zealand (12,349 ft. high).

[Footnote] † C. W. Adams: “Report on the Surveys of New Zealand for the Years 1883–84,” Appendix No. 1, p. 3. Wellington: George Didsbury, Government Printer, 1884.

[Footnote] † Plan of Mount Cook Observatory, Wellington, in above report.

[Footnote] §In Trans. N.Z. Inst., 1902, vol. 35, p. 441, Mr. Thos. King quotes 2097.2 links west. This was the position of the dog-vane on the Bolton Street Observatory, and not that of the transit instrument.

[Footnote] * C. E. Adams: Rep. Aust. Ass. Adv. Sci., p. 93, 1904; Dunedin.

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5. In 1903–4 Dr. Otto J. Klotz* determined a number of transpacific longitudes, and included in his work Sydney, Southport, Norfolk Island, Doubtless Bay, and Bolton Street Observatory. The resulting differences of longitude and observers were,—

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Differences of Longitude. Observers.
H. m. s. s.
Bolton Street Observatory–Doubtless Bay 0 5 08.941 £ 0.045 Thomas King, Otto Klotz.
Doubtless Bay–Norfolk Island 0 22 15.000 £ 0.021 Otto Klotz, F. W. O. Werry.
Norfolk Island–Southport 0 58 01.364 £ 0.008 F. W. O. Werry, Otto Klotz.
Southport–Sydney 0 08 50.495 £ 0.016 Otto Klotz, H. A. Lenehan, W. E. Raymond.

6. These observations give the complete circuit between Wellington and Sydney direct, and between Wellington and Sydney via Doubtless Bay, Norfolk Island, and Southport, thus:—

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H. m. s. s.
Sydney–Wellington (Mount Cook) E. 1 34 16.984 £ 0.020
Mount Cook–Bolton Street W. 0 0 1.200
Bolton Street–Doubtless Bay W. 0 5 8.941 £ 0.045
Doubtless Bay–Norfolk Island W. 0 22 15.000 £ 0.021.
Norfolk Island–Southport W. 0 58 1.364 £ 0.008
Southport–Sydney W. 0 8 50.495 £ 0.016
Giving an error in the circuit of 0 0 0.016s.

7. The error 0.016s. is distributed over the differences of longitude, giving the following values:—

H. m. s.
Sydney–Wellington (Mount Cook) E 1 34 16.986
Mount Cook–Bolton Street W. 0 0 1.200
Bolton Street–Doubtless Bay W. 0 5 8.931
Doubtless Bay–Norfolk Island W. 0 22 14.998
Norfolk Island–Southport W. 0 58 1.363
Southport–Sydney W. 0 8 50.494

8. To determine the longitude of Wellington (Mount Cook), the difference Sydney–Wellington is applied to the longitude of Sydney.

The longitude of Sydney is given (a) as 10h. 4m. 49.54s. in the “British Nautical Almanac,” 1914; (b) as 10h. 4m. 49.355s. using Klotz, p. 194; and (c) as 10h. 4m. 49.366s. using Klotz, p. 194, Albrecht's adjusted value for Potsdam.

9. Hence the following values for Wellington, Mount Cook Observatory:—

H. m. s.
From 8 (a) 11 39 6.526
From 8 (b) 11 39 6.341
From 8 (c) 11 39 6.352

[Footnote] * Otto J. Klotz: Report of the Chief Astronomer for the year ending 30th June, 1905; Appendix 3; Ottawa, 1906. Otto J. Klotz: Trans. N.Z. Inst., 1906, vol. 39, Article 2, p. 49; Wellington.

[Footnote] † Th. Albrecht: “Astronomische Nachrichten,” No. 3993.

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10. Another value for Wellington is obtained from the Canadian value of Norfolk Island, of—

H. m. s.
11 11 41.146 (Klotz, p. 197).
0 22 14.998 Paragraph 7.
Doubtless Bay 11 33 56.144
0 5 8.931 Paragraph 7.
Bolton Street 11 39 5.075
0 0 1.200 Paragraph 7.
Wellington (Mount Cook) 11 39 6. 275

11. The adopted value for the longitude of Wellington, Mount Cook, is 11h. 39m. 6.31s. (= 174. 46′ 34.65”); Mount Cook–Hector Observatory, 2.04s., giving 11h. 39m. 4.27s. (= 174. 46′ 4.05”) as the adopted longitude of the Hector Observatory.

(B.) Latitude.

12. The latitude of the Hector Observatory is derived by triangulation from that of the Mount Cook Observatory, the latitude of which was determined by Mr. C. W. Adams in 1883 by zenith telescope observations of 99 pairs of stars from the Melbourne General Catalogue for 1870.

13. The latitude of the Mount Cook Observatory is S. 41. 18′; 0.59′; ± 0.05″;. *

14. The latitude of the Mount Cook initial is S. 41. 17′ 59.30″ from 3 and 4.

15. The latitude of the Hector Observatory transit pier is S. 41. 17′ 3.75″, applying the difference in latitude in 4 of 55.55s.

(C.) Height.

16. The height of the top of the transit pier at the Hector Observatory was determined by the Public Works Department, by careful levelling from the tide-gauge at the Wellington Harbour Board Wharf; and was found to be 415.643 ft. above the mean sea-level determined by the harmonic anaylsis of the tide-gauge records for the year 1909.

[Footnote] * C. W. Adams: Surveys of New Zealand, Report for 1882–83, p. 11. Wellington: Government Printer.