Astronomical Observations Made at the Observatory of Cambridge Volume 10 (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. 1839 Excerpt: ...for the sake of uniformity they have been altered, and as any error in these alterations could hardly fail of being detected in the final calculations, it has not been thought worth while to mention them particularly. The objects observed, whether the star or the limb of the planet, are in general the same for the same days as those in the Nautical Almanac for 1837, pp. 474-479 In the table of Differences of N.P.D. of the N. or S. Limb of Mars and of adjacent Stars, and concluded N.P.D. of the Center of Mars, contained in pages 52--55, the numbers in the first column refer to the numbers of the observations from which the calculations are respectively made. The Greenwich Mean Solar Times are the times of observation of the planet, deduced in the usual way from the corresponding sidereal times. The differences of N.P.D. as exhibited, are corrected for refraction, but affected with parallax, to serve by comparison with like observations at a distant parallel of latitude for correcting this element. The value of a micrometer revolution for each micrometer is that obtained in 1836, viz. 33,"400. In general the star and limb of the planet were both observed with the same micrometer, and the difference of N.P.D. is converted into arc by multiplying the difference of the micrometer readings by the above quantity. When both micrometers were used, each micrometer reading is diminished by the respective reading at coincidence with the fixed wire, and the sum of the remainders is multiplied by 33,"400. Feb. 25, 4 I observed as follows for the coincidence readings of the two micrometer-wires at the middle wire. Graduated Face of Declination Circle West. Lower Micrometer Wire Upper Micrometer Wire touching fixed Wire. touching fixed Wire, r r 9,9S9 10,054,892, ...