Stargazing: past and present . Fig. 12.—The Vernal Eeiuinox among the Cun«tdlations, ^ ^r~ bo- .-^^ Fig. 13. - Showing how the Vernal E-iumox has now passed Iroui Taurus and Ai ies. The two accompanying drawings by Professor PiazziSmyth of the position of the vernal equinox among thestars in the years 2170 and 1883 will show howprecession has brought about celestial changes which have CHAP. III.] HIPPARCHUS AND PTOLEMY. 35 not been unaccompanied by changes of religious ideasand observances in origin connected with the stars. We now come to Ptolemy. There was another instr

---

Stargazing: past and present . Fig. 12.—The Vernal Eeiuinox among the Cun«tdlations, ^ ^r~ bo- .-^^ Fig. 13. - Showing how the Vernal E-iumox has now passed Iroui Taurus and Ai ies. The two accompanying drawings by Professor PiazziSmyth of the position of the vernal equinox among thestars in the years 2170 and 1883 will show howprecession has brought about celestial changes which have CHAP. III.] HIPPARCHUS AND PTOLEMY. 35 not been unaccompanied by changes of religious ideasand observances in origin connected with the stars. We now come to Ptolemy. There was another instru-ment used by Ptolemy, and described by him, which wemay mention here; it was called the Parallactic Rules,so named perhaps because that ancient astronomer usedit first for the observation of the parallax of the consists of three rods, t) E, D F, e f, Fig. 14, two ofwhich formed equal sides of an isosceles triangle ; and

---

Size: 1478px × 1691px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No

Keywords: ., bookcentury1800, bookdecade1870, booksubjec, booksubjectastronomy