Horary Tables, for Finding the Time by Inspection; To Facilitate the Operations for Obtaining the Longitude at Sea, by Chronometers and Lunar ... and Time, by Noting the Exact Interval, by a baixar o livro de graça

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. 1827 edition. Excerpt: ...so convenient for finding the altitude, the operation will seldom be more laborious than by the common method by logarithms. The necessary data will always show the altitude within the limits of the Tables by inspection sufficiently near for the purpose of clearing the lunar distance, which, with the convenience alluded to in the Preface, when only one observer is employed, will often be more or less advantageous, exclusively of their professed utility. EXAMPLE. In latitude 17. 37' South, when the Sun's declination is 13. 47' South; required the true altitude of his centre i Operation. In lat. 17. Dec. 13. Dec. 14. At h m s h m s 32 (a) 4. 0.30 4. 1.21 (c) 33 (6) 3. 56.18 Then the difference between (A: ) and (k') is (l)=&, which being sought at the head of Table Z, and 37' (the odd miles of latitude), in left-hand margin, will give 3'-6, say 4', which added to 32. 13', gives 32. 17', the true altitude in latitude 17. 37', which was required. Remark.--If the above operation had been performed only in the nearest degree of latitude, the altitude would have been but two minutes in error, which is sufficiently near for general nautical practice. If the marginal difference be 10' or 5', the proportion must be computed.-t (0 denotes the altitude in the greater degree of latitude. % These Tables having been published in common with the Author's Nautical and Astronomical Tables (with the exception of the Table of Second Differences, which is designated by the letters SD), retain the same distinguishing letter or Roman Number as in those Tables. This has been done to prevent confusion in their use, to persons who are in possession of both works; and will otherwise account for the apparent irregularity of their distinguishing characters in..