Summary

This work is not a poem by Giorgos Seferis but a compilation of passages from the 1911 Encyclopædia Britannica, including its title page, table of contents, and public domain notices. The central content consists of scientific explanations of stellar aberration, as discovered by James Bradley in the 1720s. The text describes Bradley’s observations of the star γ Draconis, which showed an unexpected 40″ north-south shift over a year, and his eventual deduction that this motion was caused by the combination of the finite speed of light and the Earth’s orbital motion. The passages detail the failure of parallax and instrumental error to explain the phenomenon, and present analogies (falling rain, a moving carriage, an umbrella) to illustrate the principle. A reader learns the precise observational history and reasoning behind the discovery of aberration of light, including Bradley’s initial hypotheses about nutation of the Earth’s axis and variation of latitude. The text also includes a brief, unrelated reference to the authenticity of ancient Arabic poems.

Key concepts

  • Aberration of lightThe apparent displacement of a star’s position caused by the combination of the Earth’s orbital motion and the finite speed of light.
  • γ DraconisThe star Bradley observed to detect the 40″ annual north-south shift that led to the discovery of aberration.
  • Nutation of the axisAn oscillation of the Earth’s axis where the poles maintain fixed geographical positions but the axis points to varying points in the heavens.
  • Variation of latitudeA shifting of the Earth’s axis within the Earth itself, causing the geographical position of the north pole to change.
  • Solstitial colureThe great circle in the celestial sphere passing through the solstices, used by Bradley to categorize stars’ maximum positions relative to the sun’s location.
  • Rule of the shorter termA copyright principle applied to foreign works, determining public domain status based on the shorter of the work’s home country or U.S. copyright term.

From the book

For other versions of this work, see Encyclopædia Britannica . ← 1911 Encyclopædia Britannica ( 1911 ) Title page → related portals : Reference Works Shortcut : EB11 or EB1911 Notes on reading the Wikisource edition . A special disclaimer for this project . Collaboration page for contributors . 12543 1911 Encyclopædia Britannica 1911 Table of contents This work is in the public domain in the United States because it was published before January 1, 1931. This work may be in the public domain in countries and areas with longer native copyright terms that apply the rule of the shorter term to foreign works . Public domain Public domain false false← Alabama 1911 Encyclopædia Britannica , Volume 1 "Alabama" Arbitration by Montague Hughes Crackanthorpe Alabama River → See also Alabama Claims on…
He is commonly known as Rab.← Abbadie, Jakob 1911 Encyclopædia Britannica , Volume 1 'Abbahu Abba Mari → See also Abbahu on Wikipedia ; and our 1911 Encyclopædia Britannica disclaimer . 12925 1911 Encyclopædia Britannica , Volume 1 — 'Abbahu ​ ʼABBAHU, the name of a Palestinian ʼamora ( q.v. ) who flourished c . 279–320. ʼAbbahu encouraged the study of Greek by Jews. He was famous as a collector of traditional lore, and is very often cited in the Talmud.

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