1. To finde the Suns Amplitude.
In this projection, the Amplitude from the East or West is represented by the line CX, take there∣fore the distance CX in your compasses, and apply it to the line of Tangents, (counting every degree
Posthuma Fosteri the description of a ruler, upon which is inscribed divers scales: and the uses thereof: invented and written by Mr. Samuel Foster, late professor of astronomie in Gresham-Colledg. By which the most usual propositions in astronomy, navigation, and dialling, are facily performed. Also, a further use of the said scales in deliniating of far declining dials; and of those that decline and recline, three severall wayes. With the deliniating of all horizontall dials, between 30 and 60 gr. of latitude, without drawing any lines but the houres themselves.
About this Item
- Title
- Posthuma Fosteri the description of a ruler, upon which is inscribed divers scales: and the uses thereof: invented and written by Mr. Samuel Foster, late professor of astronomie in Gresham-Colledg. By which the most usual propositions in astronomy, navigation, and dialling, are facily performed. Also, a further use of the said scales in deliniating of far declining dials; and of those that decline and recline, three severall wayes. With the deliniating of all horizontall dials, between 30 and 60 gr. of latitude, without drawing any lines but the houres themselves.
- Author
- Foster, Samuel, d. 1652.
- Publication
- London :: printed by Robert & William Leybourn, for Nicholas Bourn, at the South entrance into the Royall Exchange,
- 1654.
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- Subject terms
- Astronomy -- Early works to 1800.
- Nautical astronomy -- Early works to 1800.
- Navigation -- Instruments -- Early works to 1800.
- Link to this Item
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http://name.umdl.umich.edu/A40034.0001.001
- Cite this Item
-
"Posthuma Fosteri the description of a ruler, upon which is inscribed divers scales: and the uses thereof: invented and written by Mr. Samuel Foster, late professor of astronomie in Gresham-Colledg. By which the most usual propositions in astronomy, navigation, and dialling, are facily performed. Also, a further use of the said scales in deliniating of far declining dials; and of those that decline and recline, three severall wayes. With the deliniating of all horizontall dials, between 30 and 60 gr. of latitude, without drawing any lines but the houres themselves." In the digital collection Early English Books Online. https://name.umdl.umich.edu/A40034.0001.001. University of Michigan Library Digital Collections. Accessed June 15, 2025.
Pages
Page 23
of the Tangents to be two degrees) and where it resteth, that shall be the Amplitude from the East or West, which will be found to be 33 gr. 22x.
Or if you lay a Ruler upon Z and X, it will cut the Circle in Y, and the distance NY being mea∣sured on the line of Chords, shall give the Ampli∣tude also.