The description and use of an universal and perpetual mathematical instrument ... shewing the most expeditious and exact method of solving all practical questions in arithmetick, trigonometry, navigation, dyalling, astronomy, &c. ... / by Benjamin Scott.

  • Scott, Benjamin, -1755.
Date:
1733
Catalogue details

Licence: Public Domain Mark

Credit: The description and use of an universal and perpetual mathematical instrument ... shewing the most expeditious and exact method of solving all practical questions in arithmetick, trigonometry, navigation, dyalling, astronomy, &c. ... / by Benjamin Scott. Source: Wellcome Collection.

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    L791] diack ; now Becaufe the Moon comes later to the Horizon every Day by 48’, therefore to the Sun’s fetting, found as'above, always add 12’, and that Sum is the Semidiurnal Arch of the Moon, or her Half Stay above the Horizon at that Time; then bring the Hair A to 12, either at Nor S inthe roth Circle, andthe Hair B to the abovefaid Hour and Minute of half the Moon’s Stay above the Horizon in the fame 19th Circle, here fcrew the Sector faft; with this Opening bring the Hair A to the Moon’s Age in the 2oth Circle, and the Hair B will fhew her fetting in the roth Circle ; or bring the Hair B to her Age in the 20th Circle, and the Hair A will cut her rifing in the 19th Circle. The Reafon of this Rule is, that Addition and Subftraction is performed in‘any Lines or Circle of equal Parts ; fee the Deifcription of the 15th and 16th Circles. Example. 1 would know the Time of the Moon’s rifing and fetting, Augufi 5, 1725. OpERATION. i The laft Change Day was Fuly 28, _ therefore on the propofed Day the Moon is 8 Days old, thefe known, I bring the Hair A to the 28th Day of Fuly, in the 11th or 14th Cir- cle, and it cuts the 2oth Circle near 26 4, where } begin and count § Days the Moon’s Age, and that Reckoning ends at 44 inthe 20th Circle, and cuts the 9th Circle at 4 H. 22’, the Time of the Sun’s fetting when he hath the fame South Declination that the Moon now hath; to this