Now suppose the sun to be in the same latitude as the Pleiades on some particular day; owing to the proximity of the group to the ecliptic, it will be then very near the sun, and it will set with it and be invisible during the night. If the sun were to the east of the Pleiades they would have already set, and the first view of the heavens at sunset would not contain this constellation; and so it would be so long as the sun was to the east, or for nearly half a year; though during some portion of this time it would rise later on in the night. During the other half year, while the sun was to the west, the Pleiades would be visible at sunset, and we immediately see how they are thus led to divide the whole year into two portions, one of which might be called _the Pleiades below_, and the other _the Pleiades above_. It is plain that the Pleiades first become visible at sunset, when they are then just rising, in which case they will culminate a little after midnight (not at midnight, on account of the twilight) and be visible all night. This will occur when the sun is about half a circle removed from them--that is, at this time, about the beginning of November; which would thus be the commencement of one half of the year, the other half commencing in May. The culmination of the Pleiades at midnight takes place a few days later, when they rise at the time that the sun is really on the horizon, in which case they are exactly opposite to it; and this will happen on the same day all over the earth. The opposite effect to this would be when the sun was close to the Pleiades--a few days before which the latter would be just setting after sunset, and a few days after would be just rising before sunrise. [1] Mr. Haliburton's observations are contained in an interesting pamphlet, entitled _New Materials for the History of Man_, which is quoted by Prof. Piazzi Smyth, but which is not easy to obtain. It may be seen, however, in the British Museum.