DIY History | Transcribe | Scholarship at Iowa | Eccentricity of the Sextant by Frederic Furbish, 1893 | Eccentricity of the Sextant by Frederic Furbish, 1893, Page 60

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Eccentricity of the Sextant by Frederic Furbish, 1893

Eccentricity of the Sextant by Frederic Furbish, 1893, Page 60

[page]63[/page]
(2) Sun method.
The first method may be explained thus;-- Direct the telescope to a star. Bring the reflected image into the field, clamp the Vernier and bring the images into coincidence by means of a [underlined]direct[/underlined] motion of the tangent screw. (A [underlined]direct[/underlined] motion should [underlined]always[/underlined] be used in bringing direct and reflected images into coincidence or a position of tangency). Read the arc. Most arcs are graduated 10 or 15 degrees to the right of the zero mark. On some instruments the graduations are read from 0 directly to the right thus 5°, 10°, 15° etc. while on others this position of the arc is numbered as though the numbers were continuous around the circle reading 0° or 360°, 355°, 350° 345° etc.

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[page]63[/page] (2) Sun method. The first method may be explained thus;-- Direct the telescope to a star. Bring the reflected image into the field, clamp the Vernier and bring the images into coincidence by means of a [underlined]direct[/underlined] motion of the tangent screw. (A [underlined]direct[/underlined] motion should [underlined]always[/underlined] be used in bringing direct and reflected images into coincidence or a position of tangency). Read the arc. Most arcs are graduated 10 or 15 degrees to the right of the zero mark. On some instruments the graduations are read from 0 directly to the right thus 5°, 10°, 15° etc. while on others this position of the arc is numbered as though the numbers were continuous around the circle reading 0° or 360°, 355°, 350° 345° etc.