Astronomical Observations Made at the Observatory of Cambridge Volume 16 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1850 Excerpt: ... discordance of zenith points and error of assumed colatitude by the Table in page xxxvi. Transits of known stars were taken from time to time in 1844 with the Circle and the clock Molyneux, for the purpose of ascertaining the error of position of the Circle, the sidereal times of transit across the mean of the wires being obtained by the intervention of comparisons of Molyneux with Hardy. The following are the names and approximate N.P.D. of the Stars employed, with the calculated excesses of the observed times of transit across the mean of the wires above the times of meridian transit. The Circle was taken from the wall on May 27 at 22h. The above results exhibit discordances which may be partly owing to inaccurate comparisons of the clocks, and probably in some instances to mistakes of integral seconds in the counting. They, however, suffice to shew that the plane of motion of the mean of the wires nearly coincided with the meridian during the whole of the year, and it has, therefore, been thought unnecessary to calculate corrections of the Moon's N.P.D. for error of position of the Circle. The Greenwich Mean Solar Time of transit of Centre, is found by adding to the equivalent, in mean time, of the sidereal time of transit of centre, the next preceding mean time of transit of the first point of Aries, diminished by 23s,48, as the Cambridge Observatory is 23,"54 east of the Greenwich Observatory. For greater expedition the seconds of the Greenwich Mean Solar Time are generally found by adding together %52, ( = 60"--28,"48), the seconds of the mean time of transit of the first point of Aries, and the seconds of the mean time equivalents, the hours and minutes being extracted from the approximate mean times of meridian passage ...