A Treatise on Practical Astronomy: As Applied to Geodesy and Navigation |
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Page ix
... TELESCOPE . Description of instrument .. 478 Adjustment of instrument The observing list ....... Directions for observing ... 481 484 48- Value of micrometer screw . 488 Value of micrometer when level is not known .. 493 General formulę ...
... TELESCOPE . Description of instrument .. 478 Adjustment of instrument The observing list ....... Directions for observing ... 481 484 48- Value of micrometer screw . 488 Value of micrometer when level is not known .. 493 General formulę ...
Page 180
... telescope is directed to any object . The true position of the object is given by the direction of the line C'n , while the reading of the circle gives the direction Cn , differing from the former by the small angle n ' Cn CnC ' . = Let ...
... telescope is directed to any object . The true position of the object is given by the direction of the line C'n , while the reading of the circle gives the direction Cn , differing from the former by the small angle n ' Cn CnC ' . = Let ...
Page 184
... telescope , and at the same time the image of the same object , or of a second one , reflected from the silvered part of the mirror . In order to make these images equally distinct an adjusting - screw is provided ( not shown in the ...
... telescope , and at the same time the image of the same object , or of a second one , reflected from the silvered part of the mirror . In order to make these images equally distinct an adjusting - screw is provided ( not shown in the ...
Page 186
... telescope is then directed to one of the objects , which is seen through the unsilvered part of the horizon - glass , and the index - arm is revolved until the re- flected image of the second object is brought in contact with the direct ...
... telescope is then directed to one of the objects , which is seen through the unsilvered part of the horizon - glass , and the index - arm is revolved until the re- flected image of the second object is brought in contact with the direct ...
Page 187
... telescope in a direction at right angles to its axis . 105. The arc of the sextant may be extended to an entire circumference , and the index - arm produced so as to carry a A HAA B FIG . 21. - THe Prismatic Sextant . vernier at each ...
... telescope in a direction at right angles to its axis . 105. The arc of the sextant may be extended to an entire circumference , and the index - arm produced so as to carry a A HAA B FIG . 21. - THe Prismatic Sextant . vernier at each ...
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Common terms and phrases
accuracy altitude angle applied approximation arithmetical mean ascension and declination axis azimuth Bessel catalogue celestial sphere centre chronograph chronometer circle circumpolar stars clamp co-ordinates coefficients collimation computation constant convenient culmination determined difference differential dt dt earth east ecliptic elongation emersion ephemeris equal example follows formulę geocentric given gives Greenwich horizon hour-angle instant latitude limb logarithms longitude mean solar measured meridian method micrometer middle thread moon moon's right ascension multiplied Nautical Almanac obtained occultation parallax plane position prime vertical probable error proper motion reading reduced refraction right ascension screw semidiameter sextant sidereal sin² star's stars observed Substituting subtract telescope tion transit instrument unknown quantities values vernier weight write zenith distance ΙΟ
Popular passages
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