Schlagintweit, Hermann von; Schlagintweit, Adolf; Schlagintweit, Robert von: Results of a scientific mission to India and High Asia: undertaken between the years MDCCCLIV and MDCCCLVIII, by order of the court of directors of the hon. East India Company (Band 1): Astronomical determinations of latitudes and longitudes and magnetic observations: during a scientific mission to India and High Asia (Leipzig, 1861)

SECTION III.

METHOD OF DETERMINATION OF THE MAGNETIC ELEMENTS.

I. Declination. A. Instruments: a. Declinometers; b. Universal Magnetometer; c. Magnetic Needle, in Theodolite 3,

Troughton; d. Prismatic Compasses; e. Needles for daily variation. B. Method of Calculation.
II. Horizontal Intensity. Method of Observation and Calculation, including the description of the apparatuses
used.

III. Dip and Vertical Intensity. A. Dip: a. Dip Circles used; b. Comparison of the Dip Needles at Bombay,
Simla, and Srinagger; c. Example. B. Vertical Intensity.

IV. Total Intensity.

I. DECLINATION.

A. INSTRUMENTS.

The true meridian being fixed by one of the methods detailed p. 94, the
magnetic meridian was determined.
We used:

a. Two Declinometers, with two collimator magnets, marked 1 and 2.

b. Universal Magnetometers, by Barrow and Lamont.

c. The Needle in Theodolite 3, Troughton.

d. In a few instances, Troughton's Prismatic Compasses, marked 4 and 6.

e. Various Cylindrical Needles, for daily variations.

a. DECLINOMETERS.

The declinometers we used were those generally adopted in English magnetic
surveys, the construction of which, as well as that of the other magnetic instruments,

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