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THE second point requiring attention relates to time, and indicates the date when the event will take place, and the period during which its effect will continue: these are to be ascertained in the following manner.
It must however be premised, that as an eclipse, occurring at any particular season, cannot happen in all climates at the same temporal or solar hour, 1 so neither will the magnitude of the obscuration, nor the time of its continuance, be equal in all parts of the world. First, therefore (as is done in a nativity), the angles are to be arranged, in every country connected with the eclipse, according to the hour at which the eclipse, takes place and the elevation of the pole in that country. The time, during which the obscuration of the eclipse may continue in each country, is then to be noted in equatorial hours. 2 And, after these particulars have been carefully observed, it is to be understood that the effect will endure as many years as the obscuration lasted hours, provided the eclipse was solar; but if lunar, a like number of months is to be reckoned instead of years.
The commencement of the effect, and the period of its general intensity, or strength, are to be inferred from the situation of the place of the eclipse with respect to the angles. For, if the ecliptical place be near the eastern horizon, the effect will begin to be manifested in the course of the first four months after the date of the eclipse; and its general height, or intensity, will take place in, or about, the first third part of the whole extent of its duration. If the ecliptical place happen to be in or near the mid-heaven, the effect will begin to appear in the second four months, and its general intensity will occur about the second third part; and, if the place should fall near the western horizon, the effect will begin in the third four months, and take its general intensity in the last third part of its whole duration. 3
Partial intensities, or relaxations of the effect, are, however, to be inferred from any combinations which may happen during the intermediate period, 1 either in the actual places where the primary cause was presented, or in other places configurated therewith. They are also to be conjectured by the various courses, or transits, of such planets as co-operate in producing the effect, by being configurated with the sign in which the primary cause was situated; and, with this view, the matutine, vespertine, or stationary position, or midnight culmination of those planets must be observed; for the effect will be strengthened and augmented by their matutine or stationary position; but weakened and diminished by their being vespertine, or situated under the sunbeams, or by their midnight culmination.
54:1 Temporal or solar hours are duodecimal parts of the Sun's diurnal or nocturnal arc, and are numbered by day from sunrise to sunset; by night, from sunset to sunrise.
54:2 Equatorial hours are the twenty-four hours of the earth's revolution on its axis. Each of them is equal in duration to the passage of 15 degrees of the Equator; and they are numbered from noon to noon. A particular explanation of the astronomical use, both of temporal and equatorial hours, is to be found in the 9th Chapter of the second Book of the Almagest; an extract from which is given in the Appendix.
54:3 The three periods of four months each, stated in this paragraph, are applicable to solar eclipses only; for lunar eclipses, these periods may be reckoned at ten days each; that number of days bearing the same proportion to a month, as four months to a year. On this point, Whalley, with his usual p. 55 inaccuracy, has asserted, that "in eclipses of the Moon, two days, or thereabouts, are equal to the four months" here reckoned in eclipses of the Sun. He adds, however, what perhaps may be true, that "lunar eclipses are by no means so powerful as those of the Sun, although more so than any other lunation."
55:1 That is to say, from any combinations of the Sun and Moon which may take place after the date of the eclipse, but before the close of its effect.