AnnualReport-1931 — Page 227

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- F 14-

VII. MAGNETIC OBSERVATIONS,

50. From the beginning of 1928 magnetic horizontal force, declination and dip have been determined at the Au Tau Station weekly, when possible. The instruments used are a magnetometer by Cook, Troughton & Simms, No. 81, and an earth inductor by the Cambridge Instrument Co. C65818. In the following table are given the annual values of the magnetic elements in 1931 as derived from 52 determinations:-

Declination (West) 0°.43′·3 Dip (North) 30° 34'-4 Horizontal Force (C.G.S. Unit) 0.37522 Vertical Force (C.G.S. Unit) 0.22164 Total Force (C.G.S. Unit) 0.43574

51. From 1931 January 1, Greenwich Mean Time has been adopted for all magnetic observations and tabulations.

52. Records from the declination, horizontal force and vertical force instruments were obtained throughout the year with but minor gaps, due chiefly to the burning out of the electric recording lamps and occasional adjustments.

53. On January 19 new base-line mirrors, obtained from England, were fitted to the horizontal force and declination instruments. The mirrors were cemented to small brass plates held by light springs against three screws, which protrude through the back-plates of the magnet boxes of the two instruments. The base-line mirrors were aligned as closely as possible with the recording mirrors of the magnets, and the three screws were so spaced that suitable adjustment of the base-line mirrors could be made without difficulty.

54. The installation of the new base-line mirror has removed all anomalies in the value of the declination base-line; permitting satisfactory hourly tabulations, of declination throughout the year. Values of the base line are given in the following table.

1

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- F 14- VII. MAGNETIC OBSERVATIONS, 50. From the beginning of 1928 magnetic horizontal force, declination and dip have been determined at the Au Tau Station weekly, when possible. The instruments used are a magnetometer by Cook, Troughton & Simms, No. 81, and an earth inductor by the Cambridge Instrument Co. C65818. In the following table are given the annual values of the magnetic elements in 1931 as derived from 52 determinations:- Declination (West) 0°.43′·3 Dip (North) 30° 34'-4 Horizontal Force (C.G.S. Unit) 0.37522 Vertical Force (C.G.S. Unit) 0.22164 Total Force (C.G.S. Unit) 0.43574 51. From 1931 January 1, Greenwich Mean Time has been adopted for all magnetic observations and tabulations. 52. Records from the declination, horizontal force and vertical force instruments were obtained throughout the year with but minor gaps, due chiefly to the burning out of the electric recording lamps and occasional adjustments. 53. On January 19 new base-line mirrors, obtained from England, were fitted to the horizontal force and declination instruments. The mirrors were cemented to small brass plates held by light springs against three screws, which protrude through the back-plates of the magnet boxes of the two instruments. The base-line mirrors were aligned as closely as possible with the recording mirrors of the magnets, and the three screws were so spaced that suitable adjustment of the base-line mirrors could be made without difficulty. 54. The installation of the new base-line mirror has removed all anomalies in the value of the declination base-line; permitting satisfactory hourly tabulations, of declination throughout the year. Values of the base line are given in the following table. 1
Baseline (Original)
- F 14- VII. MAGNETIC OBSERVATIONS, 50. From the beginning of 1928 magnetic horizontal force, declination and dip have been determined at the Au Tau Station weekly, when possible. The instruments used are a magnetome- ter by Cook, Troughton & Simms, No. 81, and an earth inductor by the Cambridge Instrument Co. C65818. In the following table are given the annual values of the magnetic elements in 1931 as derived from 52 determinations:- Declination (West) Dip (North) Horizontal Force (C.G.S. Unit) Vertical Force (C.G.S. Unit) Total Force (C.G.S. Unit)........ 0°.43′·3 30° 34'-4 0.37522 0.22164 0.43574 51. From 1931 January 1, Greenwich Mean Time has been adopted for all magnetic observations and tabulations. 52. Records from the declination, horizontal force and vertical force instruments were obtained throughout the year with but minor gaps, due chiefly to the burning out of the electric recording lamps and occasional adjustments. 53. On January 19 new base-line mirrors, obtained from England, were fitted to the horizontal force and declination instruments. The mirrors were cemented to small brass plates held by light springs against three screws, which protrude through the back-plates of the magnet boxes of the two instruments. The base-line mirrors were aligned as closely as possible with the recording mirrors of the magnets, and the three screws were so spaced that suitable adjustment of the base- line mirrors could be made without difficulty. 54. The installation of the new base-line mirror has removed all anomalies in the value of the declination base-line; permitting satisfactory hourly tabulations, of declination through- out the year. Values of the base line are given in the following table. 1
2026-05-09 07:12:00 · Baseline
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- F 14-

VII. MAGNETIC OBSERVATIONS,

50. From the beginning of 1928 magnetic horizontal force, declination and dip have been determined at the Au Tau Station weekly, when possible. The instruments used are a magnetome- ter by Cook, Troughton & Simms, No. 81, and an earth inductor by the Cambridge Instrument Co. C65818. In the following table are given the annual values of the magnetic elements in 1931 as derived from 52 determinations:-

Declination (West)

Dip (North)

Horizontal Force (C.G.S. Unit)

Vertical Force (C.G.S. Unit)

Total Force (C.G.S. Unit)........

0°.43′·3

30° 34'-4

0.37522

0.22164

0.43574

51. From 1931 January 1, Greenwich Mean Time has been adopted for all magnetic observations and tabulations.

52. Records from the declination, horizontal force and vertical force instruments were obtained throughout the year with but minor gaps, due chiefly to the burning out of the electric recording lamps and occasional adjustments.

53. On January 19 new base-line mirrors, obtained from England, were fitted to the horizontal force and declination instruments. The mirrors were cemented to small brass plates held by

light springs against three screws, which protrude through the back-plates of the magnet boxes of the two instruments. The base-line mirrors were aligned as closely as possible with the recording mirrors of the magnets, and the three screws were so spaced that suitable adjustment of the base- line mirrors could be made without difficulty.

54. The installation of the new base-line mirror has removed all anomalies in the value of the declination base-line; permitting satisfactory hourly tabulations, of declination through- out the year. Values of the base line are given in the following table.

1

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