Book contents
- Frontmatter
- Contents
- PREFACE
- MEMOIR
- TREATISE
- Chapter I The occasion, excellence, and utility of the Observation
- Chapter II Account of the Observation
- Chapter III What others observed, or might have observed, of this Conjunction
- Chapter IV It is proved that the spot observed in the Sun's disc was really Venus
- Chapter V The Examination of the apparent Longitude and Latitude of Venus from the Sun
- Chapter VI The alteration of the apparent into the true situation of Venus
- Chapter VII An Inquiry into the Time and Place of the true Conjunction of Venus and the Sun
- Chapter VIII The Demonstration of the Node of Venus
- Chapter IX The beginning, middle, and end of the Transit are shewn
- Chapter X An Examination of the Calculations of Astronomers respecting the foregoing
- Chapter XI The Calculation of Copernicus
- Chapter XII The Calculation of Lansberg
- Chapter XIII The Calculation of Longomontanus
- Chapter XIV The Calculation of Kepler
- Chapter XV Correction of the Motions according to Rudolphi
- Chapter XVI On the Diameter of Venus
- Chapter XVII On the Diameters of the rest of the Planets, of the Proportion of the Celestial Spheres, and of the Parallax of the Sun
- Plate section
Chapter II - Account of the Observation
Published online by Cambridge University Press: 05 August 2011
- Frontmatter
- Contents
- PREFACE
- MEMOIR
- TREATISE
- Chapter I The occasion, excellence, and utility of the Observation
- Chapter II Account of the Observation
- Chapter III What others observed, or might have observed, of this Conjunction
- Chapter IV It is proved that the spot observed in the Sun's disc was really Venus
- Chapter V The Examination of the apparent Longitude and Latitude of Venus from the Sun
- Chapter VI The alteration of the apparent into the true situation of Venus
- Chapter VII An Inquiry into the Time and Place of the true Conjunction of Venus and the Sun
- Chapter VIII The Demonstration of the Node of Venus
- Chapter IX The beginning, middle, and end of the Transit are shewn
- Chapter X An Examination of the Calculations of Astronomers respecting the foregoing
- Chapter XI The Calculation of Copernicus
- Chapter XII The Calculation of Lansberg
- Chapter XIII The Calculation of Longomontanus
- Chapter XIV The Calculation of Kepler
- Chapter XV Correction of the Motions according to Rudolphi
- Chapter XVI On the Diameter of Venus
- Chapter XVII On the Diameters of the rest of the Planets, of the Proportion of the Celestial Spheres, and of the Parallax of the Sun
- Plate section
Summary
Whilst I was meditating in what manner I should commence my observation of the planet Venus so as effectually to realize my expectations, the recent and admirable invention of the telescope afforded me the greatest delight, on account of its singular excellence and superior accuracy above all other instruments. For although the method which Kepler recommends in his treatise on Optics, of observing the diameter and eclipses of the sun through a plain aperture without the aid of glasses, is very ingenious, and in his opinion, on account of its freedom from refraction, preferable to the telescope; yet I was unable to make use of it, even if I had wished to do so, inasmuch as it does not shew the sun's image exactly, nor with sufficient distinctness, unless the distance from the aperture be very great, which the smallness of my apartment would not allow. Moreover I was afraid to risk the chance of losing the observation; a misfortune which happened to Schickard, and Mögling, the astronomer to the Prince of Hesse, as Gassendi tells us in his Mercury: for they, expecting to find the diameter of Mercury greater than it was reasonable to anticipate, made use of so large an aperture that it was impossible to distinguish the planet at all, as Schickard himself has clearly proved; and even though Venus gave promise of a larger diameter, and thereby in some measure lessened this apprehension, and I was able to adapt the aperture to my own convenience, yet in an observation that could never be repeated, I preferred encountering groundless fears to the certainty of disappointment.
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- Information
- Memoir of the Life and Labors of the Rev. Jeremiah HorroxTo Which is Appended a Translation of his Celebrated Discourse Upon the Transit of Venus Across the Sun, pp. 117 - 127Publisher: Cambridge University PressPrint publication year: 2010