Claudius Ptolemaeus (A.D. 90 - A.D. 168) Alexandrian scholar also known as Ptolemy was a famous Greek mathematician, astronomer, geographer and astrologer who authored several scientific treatises, including the astrological treatise known sometimes in Greek as the Tetrabiblos, which is comprised of four books that serve as one of the most important astrological texts ever written.
William Lilly, Astrologer (1602–1681)
William Lilly is an astrologer know as the father of horary astrology. He wrote the book titled, Christian Astrology. From this book, everything we know today and that we read in other books essentially comes from this one book.
Horary astrology is the ancient art of predicting or determining the answer to a question based on a chart erected at the exact time of the clearly formed question. Thus, the transiting stars in the sky answer the querent's question, but sometimes they fail to answer the question when particular factors are present in the horary chart. Astrologers generally concur with Lilly's factors for rendering a horary chart unfit for judgement:
Dr Walter Gorn Old (born 20 March 1864, at 2:06 a.m. LMT in Handsworth, England; died 23 December 1929 in Hove, England) was a notable 19th century astrologer, better known as Sepharial.
An eminent English Theosophist. Sepharial was a well-known and respected astrologer in the late 19th and early 20th centuries and wrote numerous books, some of which are still highly regarded today.
He co-authored 360 Degrees of the Zodiac Symbolized with astrologer Charubel.
He was editor of "Old Moore's Almanac", which is still published in the 21st century.
Robert Cross Smith (1795-1832) was an English astrologer writing under the pseudonym of "Raphael".
Smith was born in Bristol on March 19, 1795. Together with G. W. Graham, he published a book on geomancy in 1822. Smith wrote periodicals entitled The Struggling Astrologer in 1824, but failed to receive enough subscribers and the periodical had to be discontinued after a few issues. He compiled the failed periodical in a volume entitled The Astrologer Of The Nineteenth Century in the same year. The volume claimed to be the "sixth edition", but it is believed that editions one to five never existed. A substantially enlarged edition appeared in 1825 as the "seventh edition", with additional material attributed to "Merlinus Anglicus Junior" (Merlinus Anglicus Junior: The English Merlin Revived was the title of a 1644 book by William Lilly). It was printed by Knight & Lacey of London.
From 1827 until his death in 1832, he edited an astrological almanac, entitled The Prophetic Messenger. Also published by Smith was The Familiar Astrologer and A Manual of Astrology, both in 1828.
Smith died on 26 February 1832 in London.
His almanac continued to be edited as Raphael's Ephemeris and would become a standard work in British and US American astrology. Raphael's Ephemeris popularized the Placidian house system in the Anglosphere and in modern western astrology in general.