《Tetrabiblos》No. IiClaudius Ptolemy（Ashmand 英譯 1822）
[291] Thus, in the latitude of Alexandria, when the first point of Gemini is three temporal hours past the meridian, the 16th degree of Libra will be on the ascendant, and the aggregate times of ascension of that degree in the said latitude are 109° 3′: by subtracting 90 from this sum, the remainder will be 19° 3′, the right ascension of the mid-heaven answering to the 18th degree of Cancer.
段落 tetra-4-noii-19public-domain (Ashmand 1822)
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