which they occur, Ptolemy's scrutiny is reserved for regions where they are visible, which he argues will manifest the effects most noticeably. The period of obscuration determines the endurance of the effect, with each hour proportioning to years for a solar eclipse and months for a lunar eclipse. The location of the eclipse with relation to the horizon is then used to judge whether the effects are most prevalent at the beginning, middle or end of the period, with times of intensification identified by planetary contacts to the degree of the eclipse which occur within this period. Chapter 7 begins the examination of what type of event will manifest. This is judged by the angle of the horizon which precedes the eclipse in the chart set for the location under scrutiny and the planet(s) that dominate this angle by rulership and powerful aspectual connections. Whether the predicted effect is beneficial or destructive depends on the condition of these planets, whilst the type of manifestation is judged by the zodiac signs, fixed stars and constellations involved. The resulting prediction is of relevance to nations, but Ptolemy points out that certain individuals are more resonant to the effects than others; namely those have the Sun or Moon in their horoscopes in the same degree as the eclipse, or the degree that directly opposes it. Within his Almagest Ptolemy explains that he had access to eclipse records kept for 900 years since the beginning of the reign of king Nabonassar (747 BC). In chapter 9 of the Tetrabiblos he shows knowledge of the Babylonian lore that accompanied these records in detailing the omens based on visual phenomena. The colours of eclipses and "the formations that occur near them, such as rods, halos, and the like" are considered along with the astrological significance of comets, in whether they take the form of "'beams', 'trumpets', 'jars', and the like". Meaning is derived from their position relative to the Sun and assessment of "the parts of the zodiac in which their heads appear and through the directions in which the shapes of their tails point". It is noted that here Ptolemy uses principles that fall outside the neat theoretical logic he presents in book I, being explicable only in terms of the mythological and omen tradition inherited from his ancient sources. He also defends the subjective nature of the analysis involved, asserting that it would be