Ptolemy's Tetrabiblos : $b or Quadripartite, being four books of the influence of the stars ... with a preface, explanatory notes, and an appendix containing extracts from the Almagest of Ptolemy and the whole of his Centiloquy, together with a short notice of Mr. Ranger's zodiacal planisphere and an explanatory platePtolemy
Religion
Ptolemy's Tetrabiblos : $b or Quadripartite, being four books of the influence of the stars ... with a preface, explanatory notes, and an appendix containing extracts from the Almagest of Ptolemy and the whole of his Centiloquy, together with a short notice of Mr. Ranger's zodiacal planisphere and an explanatory plate
Ptolemy
Astrology -- Early works to 1800
The magnitude of any temporal hour may be, however, more easily found
by referring to the annexed Table of Ascensions, and taking the
difference between the respective aggregate numbers, inserted therein
under the heads of the equinoctial parallel or right sphere, and of
any particular climate for which the magnitude of the temporal hour is
required; and, if the said hour be a diurnal hour, the aggregate times
as stated against the zodiacal degree occupied by the Sun; but, if
nocturnal, those stated against the degree diametrically opposite, are
to be compared; and the sixth part of the difference between them is to
be added, if the said degree be in the northern signs, to the fifteen
times of an equatorial hour; but subtracted therefrom, if in the
southern signs. The amount thus obtained will be the required number of
degrees of the temporal hour in question.[287]
[286] Thus (according to the Table inserted at p. 152), in the climate
or latitude of Lower Ægypt, the times of ascension between the first
point of Gemini and the first point of Sagittarius, diametrically
opposite, are 205° 18′, which, being divided by 15, give 13 hours 41
minutes and a fraction of equatorial time, as the length of the day of
the first point of Gemini. And the same number of times of ascension,
divided by 12, give 17° 6′ and a fraction of the equator, as the length
of the diurnal temporal hour. In the latitude of Southern Britain, the
times of ascension between the same points as above mentioned are 236°
2′, which, divided by 15, give 15 hours 44 minutes and a fraction of
equatorial time, as the length of the day of the first point of Gemini;
and, if divided by 12, they produce 19° 40′ and a fraction of the
equator, as the length of the diurnal temporal hour.
[287] Thus, the aggregate times of ascension, in a right sphere, of
the first point of Gemini are 57° 44′; and, in the climate of Lower
Ægypt, 45° 5′: the sixth part of the difference between them is 2° 6′
and a fraction, which, added to 15°, again makes the diurnal temporal
hour of the first point of Gemini equal to 17° 6′ and a fraction of
the equator. In the climate of Southern Britain, the aggregate times
of ascension of the first point of Gemini are 29° 43′: the sixth part
of the difference between that sum and 57° 44′ of right ascension is
4° 40′ and a fraction, which, added to 15°, makes the diurnal temporal
hour of the first point of Gemini, in South Britain, equal to 19° 40′
and a fraction of the equator, as before shown.
Public-domain text, read in full here on John Shaqi.
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