Familiar talks on astronomy, with chapters on geography and navigaton . Fig. 4. Now in order to find the moons horizontalparallax, two observers, one as far north as prac-ticable and the other as far south, and both being. on the same meridian, observe the moons zenithdistance when it is on the meridian, and fromthese observations deduce the parallax required. Moons Distance Calculated. 81 In the diagram (Fig. 5) let O be the centreof the earth, PP its axis, and E Q the A be an observer in north latitude, and Ban observer in south latitude. Let M be themoon on their meridian. The o
Familiar talks on astronomy, with chapters on geography and navigaton . Fig. 4. Now in order to find the moons horizontalparallax, two observers, one as far north as prac-ticable and the other as far south, and both being. on the same meridian, observe the moons zenithdistance when it is on the meridian, and fromthese observations deduce the parallax required. Moons Distance Calculated. 81 In the diagram (Fig. 5) let O be the centreof the earth, PP its axis, and E Q the A be an observer in north latitude, and Ban observer in south latitude. Let M be themoon on their meridian. The observer at Ameasures the zenith distance Z A M; the ob-server at B, the zenith distance ZB M. Know-ing these angles we know the angles OAM andO B M. Then in the quadrilateral A O B M, weknow the angles at A and B, and the angleA O B ; also the two sides, A O, OB, they beingradii of the earth. The angle A O B, you ob-serve, is the difference of latitude of the twoobservers ; so of course we know it. Now fromthese data we can find the angle A M B. Nowthe angle A M O is what we call the parallax inaltitude at A, and the angle B M O the parallaxin altitude at B. Knowing the parallax in alti-tude, we can by an easy form
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Keywords: ., bookcentury1800, bookdecade1880, bookidfamiliartalk, bookyear1889
