The mariners magazine, or, Sturmy's mathematical and practical arts containing the description and use of the scale of scales, it being a mathematical ruler, that resolves most mathematical conclusions, and likewise the making and use of the crostaff, quadrant, and the quadrat, nocturnals, and other most useful instruments for all artists and navigators : the art of navigation, resolved geometrically, instrumentally, and by calculation, and by that late excellent invention of logarithms, in the three principal kinds of sailing : with new tables of the longitude and latitude of the most eminent places ... : together with a discourse of the practick part of navigation ..., a new way of surveying land ..., the art of gauging all sorts of vessels ..., the art of dialling by a gnomical scale ... : whereunto is annexed, an abridgment of the penalties and forfeitures, by acts of parliaments appointed, relating to the customs and navigation : also a compendium of fortification, both geometrically and instrumentally / by Capt. Samuel Sturmy.
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Title
The mariners magazine, or, Sturmy's mathematical and practical arts containing the description and use of the scale of scales, it being a mathematical ruler, that resolves most mathematical conclusions, and likewise the making and use of the crostaff, quadrant, and the quadrat, nocturnals, and other most useful instruments for all artists and navigators : the art of navigation, resolved geometrically, instrumentally, and by calculation, and by that late excellent invention of logarithms, in the three principal kinds of sailing : with new tables of the longitude and latitude of the most eminent places ... : together with a discourse of the practick part of navigation ..., a new way of surveying land ..., the art of gauging all sorts of vessels ..., the art of dialling by a gnomical scale ... : whereunto is annexed, an abridgment of the penalties and forfeitures, by acts of parliaments appointed, relating to the customs and navigation : also a compendium of fortification, both geometrically and instrumentally / by Capt. Samuel Sturmy.
Author
Sturmy, Samuel, 1633-1669.
Publication
London :: Printed by E. Cotes for G. Hurlock, W. Fisher, E. Thomas, and D. Page ...,
1669.
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"The mariners magazine, or, Sturmy's mathematical and practical arts containing the description and use of the scale of scales, it being a mathematical ruler, that resolves most mathematical conclusions, and likewise the making and use of the crostaff, quadrant, and the quadrat, nocturnals, and other most useful instruments for all artists and navigators : the art of navigation, resolved geometrically, instrumentally, and by calculation, and by that late excellent invention of logarithms, in the three principal kinds of sailing : with new tables of the longitude and latitude of the most eminent places ... : together with a discourse of the practick part of navigation ..., a new way of surveying land ..., the art of gauging all sorts of vessels ..., the art of dialling by a gnomical scale ... : whereunto is annexed, an abridgment of the penalties and forfeitures, by acts of parliaments appointed, relating to the customs and navigation : also a compendium of fortification, both geometrically and instrumentally / by Capt. Samuel Sturmy." In the digital collection Early English Books Online 2. https://name.umdl.umich.edu/A61915.0001.001. University of Michigan Library Digital Collections. Accessed June 15, 2024.
Pages
descriptionPage 48
CHAP. XXXII. How to find the Time of the Night by the Moon shining upon a Sun Dial.
HAving the Age of the Moon by the Epact; as for Example, the 9th. day of August 1665. the Epact 23, to which add 9 the day of the Month, and 6 the Months from March, makes 38; from it substract 29 a whole Moon, with 12 ho. 44 min. which multiply the remaining 9 by 4, makes 36; that divide by 5, and you have 7 ho. and 12 min. for the odd Unite, and 24 min. for the half day, or 12 hours added together, makes 7 ho. 36 min. for the Moon being South.
Now having the Moons coming to the South by the former way, add this Southing of the Moon and the Shadow of the Moon upon the Dial together, and that is the time of the Night. If the Sum exceed 12 Hours, take only the overplus.
* 1.1Or thus you may do: If the Moon be 9 days old at Noon, she will be 9 days and an half at night; therefore you may add about a quarter or half an hour thereunto, as it is more early or late in the night, and add the Southing of the Moon, which makes 7 ho. 30 min. added to the Shadow of the Moon 3 ho. upon the Sun-dial, it makes 10 ho. 30 min. for the time of the night: So you see there is 6 min. difference betwixt these two ways, which cannot well be estimated; but either way will give neer enough satisfaction for the time of the Night.