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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    Cs J Day, and where it cuts upon Circle 20, count in that Circle fo many Days forward asthe Moon is old; where that Reckoning ends, lay the Hair -of the other Leg of the Sector, and it will cut the Circle of Signs (viz. the 5th Circle) in the Sign and Degree of the Moon’s Place in Lon- gitude, with refpect to the laft-Conjunction ; but, becaufe the Sun moves near a Degree in a Day the Year round, therefore to the Sign and Degree of the Zodiack above found, add fo many Degrees as the Moon is Days old, and you will have her Place pretty near the Truth ; nay near enough in a Work of this Nature: And that Place fo found, wil] be to the fame Time of the Day that the lait Conjunction was at ; .4.e. if the laft Conjunction of the Sun and Moon was at eight in the Morning, then the Moon’s Place in Longitude found by this In- ftrument 1s alfo at eight o’ Clock in the Morning on that Day propofed. Example, Y would know the Moon’s Place in Longitude on the 10th Day of Yuly 1725. By the Method in pag. 69, I find the laft New Moon was upon une 28, to which I lay one of the Hairs of the Sector in the 12th Circle, and it cuts the 2oth Circle at a little more than 24; here begin and count forward in this Circle as many Days as the Moon is old, which in this Example are 12, fo I call25 one, 26 two, and fo on; {fo that the Moon’s Age 12 ends at a lit- tle more than 6 in the 20th Circle, to this I bring the other Hair of the Sector, and it then cuts the 5th Circle of Signs at ¥ 11°, to ie ad.
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