set, and are found in each revolution once on the meridian above the earth, and once on that below the earth. In all these cases, the time occupied in proceeding round from any angle to the same again, must be everywhere equal in its duration, for it is marked by one sensible revolution; and the time occupied in passing from either meridianal angle to the angle diametrically opposite, is also everywhere equal; because it is marked by the half of one revolution. So, also, the passage from either horizontal angle to its opposite angle is again effected in the same equal portion of time, wherever the equator may be in the zenith, for it is then likewise marked by the half of an entire revolution; because on such a position of the equator, all the parallels are then divided, as well by the horizon as by the meridian, into two equal parts. But in all other declinations, the time of passage of a semicircle above the earth is not equal to that of its passage below the earth, except only in the case of the equinoctial circle itself, which, in an oblique sphere, is the only one divided by the horizon into two equal parts, all others (its parallels) being bisected into dissimilar and unequal arcs. It follows, accordingly, that the time contained in the space between rising or setting, and either meridian, must be equal to the time between the _same_ meridian and rising and setting; because the meridian divides equally such portions of the parallels as are above or under the earth. But in proceeding in an _oblique_ sphere, from rising or setting to _either_ meridian, the time occupied must be unequal; and in a right sphere, equal, because the entire portions above the earth are, in a _right_ sphere only, equal to those below the earth; whence, for instance, in a right sphere, whatever stars may be together on the meridian must also all rise and set together, until their progress becomes perceptible by the poles of the zodiac; while, on the other hand, in an oblique sphere, whatever stars may be together on the meridian can neither all rise together nor set together; for the more southern stars must always rise later than those which are more northern, and set earlier.[285] [285] On this side of the equator. The aspects made by the fixed stars, in regard to the planets or parts of the zodiac, and the earth combined, are considered, in a general manner, by the rising, or meridianal position, or setting of the same fixed stars in conjunction with any planet or part of the zodiac; but their aspects are properly distinguishable, by means of the Sun, in the nine following modes:—