Speculum nauticum a looking glasse for sea-men : wherein they may behold a small instrument called the plain scale whereby all questions nautical and propositions astronomical are very easily and demonstratively wrought ... / by Iohn Aspley.

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Title
Speculum nauticum a looking glasse for sea-men : wherein they may behold a small instrument called the plain scale whereby all questions nautical and propositions astronomical are very easily and demonstratively wrought ... / by Iohn Aspley.
Author
Aspley, John.
Publication
London :: Printed by Thomas Harper and are to be sold by George Hurlock,
1647.
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Subject terms
Navigation -- Early works to 1800.
Nautical astronomy.
Link to this Item
http://name.umdl.umich.edu/A26045.0001.001
Cite this Item
"Speculum nauticum a looking glasse for sea-men : wherein they may behold a small instrument called the plain scale whereby all questions nautical and propositions astronomical are very easily and demonstratively wrought ... / by Iohn Aspley." In the digital collection Early English Books Online. https://name.umdl.umich.edu/A26045.0001.001. University of Michigan Library Digital Collections. Accessed May 12, 2025.

Pages

Page 46

CHAP. XII.

The elevation of the Pole, the Almicanter, and decli∣nation of the Sun, being given to finde the houre of the day.

The elevation of the Pole is 30 degrees, the declination of the Sun is 20 degrees, the Almicanter of the Sun is 48. degrees, and 18 minutes, the houre of the day is found as followeth, by the ninth Demonstration.

FIrst, upon the centre A. draw the circle B. C. D. E. then draw the Diameter B. D. re∣presenting the Horizon, then from D. unto R. set 30 degrees, the elevation of the Pole, then from R. by the Point A. draw the line R. A. S. representing the Pole of the World, then draw the line F. A. H. crossing the Pole in A. at right Angles, cutting the Meredian Line in F. then from F. set 20 degrees, the declination of the Sun unto L. and then from the point L, draw the Line LPO, representing the parallell of the Sunne, and cutting the Pole of the World in P, then placing one foot of your Compas∣ses in P, extend the other unto L, with which distance of your Compasses, draw the houre circle I, NOQ, then from the Horizon at B, place the Suns Almi∣canter: (which is 48 degrees, and 18 minutes) upon the Quadrant BGL, from B, unto G, then from the point G, draw the line GI, parallell unto the Hori∣zon BAD, cutting the line LO, in I, then from the point I, draw the line KIM, parallell to the Pole of the World QAN, cutting the circle LNO, in M, then let IN, be divided into 6 houres, whereof LM, are three: whereupon I conclude, that it is three houres from noon, that is, at nine a clock in the morning, or three in the afternoone.

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