The astrolabe /
by James E. Morrison.
- [First edition].
- iv, 438 pages : illustrations ; 28 cm
Includes bibliographical references (pages 415-419) and index.
1. The astrolabe : What is an astrolabe? ; An instrument with a past and a future ; The principle of the astrolabe ; The parts of the astrolabe : The front of the astrolabe ; The rete and rule ; The back of the astrolabe. An illustrated example ; Types of astrolabes : The spherical astrolabe ; The planispheric astrolabe ; Universal astrolabes ; Astrolabe quadrants ; Horizontal instruments ; Astrolabe clocks ; Computer astrolabes -- 2. A concise history of the astrolabe : Foundations of the astrolabe: origins of the stereographic projection ; Development of the astrolabe : Prayer times ; Astrology. Refinement of the astrolabe ; Decline of astrolabe popularity -- 3. The stereographic projection : Principle of the stereographic projection ; Why the astrolabe works ; Application of the stereographic projection to the planispheric astrolabe ; The half angle theorem ; Stereographic projection proofs -- 4. The planispheric astrolabe front : The mater and throne ; The limb ; The plate : Plate interior ; Twilight arcs ; Unequal hours ; Other hour arcs ; "House of Heaven ; Plate latitude. Some special plates : The plate of horizons ; Plate for 0 degrees and 90 degrees ; Plate of ecliptic coordinates -- 5. Drawing the astrolabe plate : The equator and the tropic of Cancer ; Horizon and almucantar projection : Graphical horizon construction ; Altitude circle (almucantar) projections ; Almucantar center projection ; Graphical altitude circle (almucantar) projections ; Almucantar alignment with meridian ; Almucantar separation. Azimuth arc projections : Graphical Azimuth arc construction. Unequal hour arcs ; Islamic prayer times ; Equal hour arcs ; Houses of Heaven ; Other graphical layout methods : The Dastur ; Hartmann's method -- 6. The rete : Precession ; The Ecliptic ; Dividing the Ecliptic ; Star positions : Mediation. A modern rete ; A celestial navigator's rete -- 7. The rule : Making the rule -- 8. The astrolabe back : The back of European astrolabes : The altitude scale ; The solar longitude scale ; The calendar ; Eccentric calendar ; Drawing the eccentric calendar ; Concentric calendar ; Drawing the concentric calendar ; The shadow square ; Drawing the shadow square ; The diagram of unequal hours ; Using the unequal hours diagram ; Equal hour scale ; Equal/unequal hour scale ; Using the equal/unequal hour scale ; Drawing the equal/unequal hour scale. The back of Islamic astrolabes : Shadow scales ; The sine/cosine scale ; Using the sine/cosine scale ; Making the sine/cosine scale ; The cotangent scale ; Using the cotangent scale ; Drawing the cotangent scale ; The arcs of the signs ; The sun's noon altitude curves ; Drawing the sun's noon altitude curves ; The graph of the Azimuth of the qibla ; Drawing the graph of the qibla. Other scales on the back of Islamic astrolabes : Lunar mansions ; Calendars ; Astrological scales. A modern astrolabe back : Using the modern astrolabe back ; Making the modern astrolabe back -- 9. Sample problems : The astrolabe as a teaching tool -- 10. The astrolabe for southern latitudes : The plate ; The rete ; The rule -- 11. Calculation summary : Tropics ; Horizon ; Almuncatars ; Azimuths ; Rete ; How accurate is an astrolabe? -- 12. Universal astrolabe -- 13. The Saphea Arzachelis : The saphea universal astrolabe : Saphea scale ; Parallels ; Polar arcs ; The regula and braciolus ; Uses of the saphea ; The planispheric astrolabe. Making the saphea ; The lamina universal and the "mathematical jewell" ; Peter Apian's "Meteoroscope" ; The quadratum nauticum -- 14. Orthographic astrolabes : The orthographic projection ; The Organum Ptolemei ; The orthographic astrolabe : The origins of the Rojas astrolabe. The Rojas astrolabe : Using the Rojas astrolabe ; Making the Rojas astrolabe ; The regula and cursor -- 15. De la Hire's astrolabe : Using the de la Hire astrolabe ; Making the de la Hire astrolabe ; Calculation example. 16. Quadrants : Introduction ; The Horary quadrant (quadrans vetus) : History of the Horary quadrant ; Making a Horary quadrant ; Accuracy of the Horary quadrant -- 17. The astrolabe quadrant : The principle of the astrolabe quadrant ; The quadrans novus ; The quadrans novus arcs and scales : The quadrans novus interior ; Scales ; Stars ; Right ascension. Using the quadrans novus : Position-related problems ; Time-related problems. Making the quadrans novus -- 18. The Prophatius quadrant : Using the Prophatius quadrant ; Making the Prophatius quadrant -- 19. Gunter's quadrant : Description ; Using Gunter's quadrant ; Making Gunter's quadrant -- 20. Sutton's quadrant : Description ; Using Sutton's quadrants ; Making Sutton's quadrants ; Sutton's "small quadrant" -- 21. Horizontal Instruments : Description ; Hartmann's "compast" ; Time measurement with the horizontal instrument ; Oughtred's double dial ; Using the horizontal instrument ; Using the double dial ; Making the horizontal instrument ; The horizontal projection quadrant -- 22. Astrolabe variations : Van Maelcote's astrolabe : Using van Maelcote's astrolabe ; Making van Maelcote's astrolabe. The linear astrolabe of al-Tusi ; Islamic astrolabe variations ; Planisphere : Making a planisphere. Other astrolabe related devices -- 23. Astrolabe clocks : Monumental astrolabe clocks ; Personal clocks with astrolabe dials ; The Ulysse-Nardin "Astrolabium Galileo Galilei" -- 24. Astronomical background : The celestial sphere : Equatorial coordinates ; Ecliptic coordinates ; Mediation. The sun's position ; Time ; Telling time ; Sidereal time -- 25. Astronomical calculations : Transformation of coordinates ; Time in astronomical calculations : The origin of the Julian period ; Uses of the Julian period ; Calculating Julian days. The sun's position ; Stellar precession ; The equation of time ; Calculating time -- 26. Computers and astrolabes : Simple astrolabe programs ; Some useful routines : Drawing a circle from three points ; Clipping circles ; Ecliptic division -- 27. Design, layout and fabrication : Design ; The back ; Fabrication alternatives.