Edinburgh Royal Observatory
Published: 2013-09
Total Pages: 42
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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1843 edition. Excerpt: ...of Axis (interpolated from Table II.), then when the South mark has been observed; a=s+s- =-o-77+s- ... (6) when the North mark has been observed; os=-Jv"-n+c =-o-57-n+c.... (7) when both marks have been observed; a=j (s-iv"+s-n)=-o-67+j (s-n).. (8) The values of m have been determined from one of the following expressions: m = cot Lat. + a cosec Lat (9) tan Lat. + secant Lat (10) The former was employed on those days when the deviation from the Pole n, and the azimuth a, had been ascertained from observations of the meridian marks, given in Table I.; and the latter, on those days when n had been ascertained, but not a, b being interpolated from Table II. In the first case, m is stated, in Table III., to have been determined from a; in the second from b. Sometimes m has been determined from both expressions, and a mean of the results taken, in which case m is stated, in the same Table, to have been determined from a and b. The values of m, n, and c, employed in computing the correction of the Instrument, according to the formula (2), are contained in the following Table HI. The asterisks there annexed to some of the dates denote that on those days, there being no determinations of the values of n or a, means of the preceding and subsequent values of m and n have been taken and inserted in the Table. The correction of the Instrument for the Moon has been ascertained by increasing the correction for a Star, having the same Declination as the apparent Declination of the Moon, in the proportion of the interval between the Star's transit over two Wires to the observed interval between the Moon's transit over the same Wires. The value of b is found immediately from the spirit-level. In...