The planetary hours

for almost all Astrologers divide all that space of time from the Sun rising to setting into twelve equall parts, and call them the twelve hours of the day; then the time which followeth from the setting to the rising, in like manner being divided into twelve equall parts, they call the twelve hours of the night, and then distribute each of those hours to every one of the Planets according to the order of their successions, giving alwayes the first hour of the day to the Lord of that day, then to every one by order, even to the end of twenty four hours

In plain English Daylight is cut into twelve equal parts and the night into twelve more. Because daylight and night are rarely the same length, an hour of the day and an hour of the night are rarely sixty minutes and rarely equal to one another: they stretch and shrink with the season and the latitude, and only at an equinox does an hour run to sixty minutes.

If you begin at the first hour to count the hours of the day and of the night, assigning the first to Saturn, the next to Jupiter, the third to Mars, the fourth to the Sun, the fifth to Venus, the sixth to Mercury, and the seventh to the Moon, 2  according to the order of the cycles which the Egyptians observe, and if you repeat the process, you will find that the first hour of the following day comes to the Sun. 3  And if you carry on the operation throughout the next twenty-four hours in the same manner as with the others, you will dedicate the first hour of the third day to the Moon, and if you proceed similarly through the rest, each day will receive its appropriate god.

In plain English Run the seven planets in the order Saturn, Jupiter, Mars, Sun, Venus, Mercury, Moon, one to each hour, starting again at Saturn after the seventh. Twenty-four hours is three whole cycles and three hours over, so each day begins three places further along than the last — which is why the weekdays run Saturn, Sun, Moon rather than in the order of the spheres, and why the day takes the name of the planet of its first hour.

but in the partition of the hours some do different, saying, that the space of the rising and setting is not to be divided into equall parts, and that those hours are not therefore called unequal because the diurnal are unequal to the nocturnall, but because both the diurnal and nocturnal are even unequall amongst themselves; therefore the partition of unequall or Planetaty hours hath a different reason of their measure observed by Magicians, which is of this sort; for as in artificiall hours, which are alwayes equall to themselves, the ascensions of fifteen degrees in the equinoctiall, constituteth an artificial hour: so also in planetary hours the ascensions of fifteen degrees in the Eclipticke constituteth an unequall or planetary hour, whose measure we ought to enquire and find out by the tables of the oblique ascensions of every region.

In plain English Agrippa records a disagreement rather than settling it. Some held that daylight should not be cut into twelve EQUAL parts at all, and that the hours are called unequal because they are unequal among themselves — the measure being the rising of fifteen degrees of the ecliptic, read from tables of oblique ascension for the place. This page computes the first method, which is the one almost every later book means, and says so.