Description
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. 1851 Excerpt: …the same or of a different denomination, and it will give the true latitude of the place required. Take the middle latitude between the starting point and that for which the difference of longitude is required, and correct the value of one minute or second in the Table, for the number in the column designated distance from equator, corresponding nearest to that of the middle latitude. Divide the Tabular difference of longitude reduced to feet by the corrected value of one minute or second, and the quotient will give the difference of longitude in arc required; which being added to, or subtracted from, the longitude (from Greenwich) of the starting point as above, will give the true longitude of the place required. Lat. of Hatras N. 27 36′; value of 1′ of lat. for 28, in Table C= 6059-1 and 17107-068 + 6059-1 gives 02-8233′, or N. 02′ 49-40, nearly, for the diff. of latitude in arc, which added to the latitude of the starting point (being of the same denomination) gives N. 27 36′ + N. 02′ 49-40, or N. 27 38′ 4940 for the true latitude of Duriapoor. Again, for the difference of longitude in arc: Latitude of Hatras N. 27 36′ Half diff. of lat. of Duriapoor N. 01-41167 Now 1, or 60′: –48-9 feet:: 37-41167′: –30-49, and 5426-2–30-49 = 5395-71 feet, value 1′ of longitude to middle latitude: then, using this number as a divisor, we shall have the tabular difference of longitude reduced to feet 21689-976 + 5395-71 = 4-018′, or 04′ 01-08 E., the difference of longitude in arc, which added (as above) to the longitude (east of Greenwich) of Hatras (78 04′) gives 78 08′ 01-08 E. for the true longitude of Duriapoor. The latitude should be found by celestial observation at least once in twenty-four hours, and if the meridi…
