DIY History | Transcribe | Scholarship at Iowa | Theory of the astronomical transit instrument applied to the portable transit instrument Wuerdemann no.26: a compilation from various authorities, with original observations by Harry Edward Burton, 1903 | Theory of the astronomical transit instrument applied to the portable transit instrument Wuerdemann no. 26: a compilation from various authorities, with original observations by Harry Edward Burton, 1903, Page 42

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Theory of the astronomical transit instrument applied to the portable transit instrument Wuerdemann no.26: a compilation from various authorities, with original observations by Harry Edward Burton, 1903

Theory of the astronomical transit instrument applied to the portable transit instrument Wuerdemann no. 26: a compilation from various authorities, with original observations by Harry Edward Burton, 1903, Page 42

   (c) Next set the telescope for some Almanac star which is soon to cross the meridian within ten degrees of the pole. It will appear to move very slowly. Compute its clock time of transit, using the clock correction just found. Let α= the right ascension and Δt= the value of the clock correction. Then α=t+Δt, and t=α-Δt= the star's clock time of transit. As the time approaches bisect the star with the middle vertical wire of the reticle and keep it bisected, following the motion of the star in azimuth by means of the azimuth screw, the slow motion screw which gives a slight horizontal motion to one of the eyes, until the clock indicates that the star is on the meridian.
   If the clock correction had been known with absolute exactness, the instrument would now be truely in the meridian. As the clock error, however, is only approximate, the instrument will be only approximately in the meridian; but it will be very much

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(c) Next set the telescope for some Almanac star which is soon to cross the meridian within ten degrees of the pole. It will appear to move very slowly. Compute its clock time of transit, using the clock correction just found. Let α= the right ascension and Δt= the value of the clock correction. Then α=t+Δt, and t=α-Δt= the star's clock time of transit. As the time approaches bisect the star with the middle vertical wire of the reticle and keep it bisected, following the motion of the star in azimuth by means of the azimuth screw, the slow motion screw which gives a slight horizontal motion to one of the eyes, until the clock indicates that the star is on the meridian. If the clock correction had been known with absolute exactness, the instrument would now be truely in the meridian. As the clock error, however, is only approximate, the instrument will be only approximately in the meridian; but it will be very much