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chapter:
INTRODUCTION
CHAPTER I: THE ZODIAC AND THE PLANETS
CHAPTER II: THE PHASES OF THE MOON
CHAPTER III: THE COURSE OF THE SUN THROUGH THE TWELVE SIGNS
CHAPTER IV: THE NORTHERN CONSTELLATIONS
CHAPTER V: THE SOUTHERN CONSTELLATIONS
CHAPTER VI: ASTROLOGY AND WEATHER PROGNOSTICS
CHAPTER VII: THE ANALEMMA AND ITS APPLICATIONS
CHAPTER VIII: SUNDIALS AND WATER CLOCKS
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BOOK I
BOOK II
BOOK III
BOOK IV
BOOK V
BOOK VI
BOOK VII
BOOK IX
1. IN distinction from the subjects first mentioned, we must ourselves explain the principles which govern the shortening and lengthening of the day. When the sun is at the equinoxes, that is, passing through Aries or Libra, he makes the gnomon cast a shadow equal to eight ninths of its own length, in the latitude of Rome. In Athens, the shadow is equal to three fourths of the length of the gnomon; at Rhodes to five sevenths; at Tarentum, to nine elevenths; at Alexandria, to three fifths; and so at other places it is found that the shadows of equinoctial gnomons are naturally different from one another.
Vitruvius: The Ten Books on Architecture. Vitruvius. Morris Hicky Morgan. Cambridge: Harvard University Press. London: Humphrey Milford. Oxford University Press. 1914.
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