10J3 



ZODIAC. 



ZODIAC. 



1054 



being by steps in the interior. Bas-reliefs, apparently of an astrono- 

 mical character, are found in several other apartments within the same 

 temple ; and in the ceiling of its portico are figures resembling constel- 



lations, among which are those of the zodiac disposed in two lines, one 

 near each extremity of the portico, and parallel to the longitudinal axis 

 of the temple. 



The zudiacal figures in the apartment first mentioned are disposed 

 nearly within the breadth of an annulus formed by two circles, whose 

 common centre is at some distance southward from the centre of the 

 while ; the figure which is conceived to represent Cancer is however 

 within the space inclosed by the interior circumference of the annulus, 

 and nearly opposite the interval between Gemini and Leo ; that interval 

 being occupied by a human figure with a bird's head, above which are 

 a liinl and certain hieroglyphical symbols. The figure of Cancer is also 

 surmounted by a hieroglyphical symbol, which, according to Visconti, 

 seenu to express a proper name. 



Except the zodiacal figures, scarcely any In the ceiling resemble those 

 which are now assigned to the constellations ; and a great effort of the 

 imagination is required to discover in what manner they may be con- 

 sidered n emblems of the latter. From the zodiacal figures only has 

 it been possible to form opinions concerning the nature of the projec- 

 tion employed in the execution of the work, and the epoch to which 

 the aspect of the heavens represented by it is to be referred. 



The first discoverers of this ancient monument immediately per- 

 ceived that the horary or declination circles, if drawn upon it, would 

 be represented by straight lines diverging from the centre : the latter 

 is consequently the pole of the equator ; but we are indebted to M. 

 Biot (' Recherches sur 1'Astronomie Kgyptienne ') for the very probable 

 idea that the space within the exterior circle represents a development 

 of the whole surface of the celestial sphere, the radii of the circle being 

 equal to half the circumferences of the hour circles, so that the exterior 

 circle represents the south pole of the equator in the heavens. The 

 figures of the constellations are supposed to be placed on the radii 

 corresponding to the circumferences of the hour circles passing through 

 the groups of stars to which the figures belong, and at distances from 

 the centre of the planisphere equal to the angular distances of the 

 figures from the north pole of the equator. The distortion produced 

 by uch a development of a spherical surface is evidently very great 

 near the margin ; but a spectator when duly instructed, on comparing 

 the figures near the centre with the groups of stars about the north 

 pole in the heavens, might distinguish those to which the figures were 



intended to refer ; and the apartment without a roof, adjoining that 

 which contained the planisphere, is supposed to have been intended 

 for the purpose of facilitating such comparison. One property of the 

 species of projection or development just mentioned is, that in the direc- 

 tion of a line passing through the centre, or pole, the distance between 

 two points corresponding to two which are diametrically opposite to 

 one another in the heavens is equal to half the circumference of a gre.it 

 circle of the sphere ; and M. Biot found that this condition is satisfied 

 by the planisphere as nearly as can be expected in a representation 

 which does not admit of great precision. 



In order to ascertain, if possible, the epoch of the planisphere, M. 

 Biot assumed as correct the positions of four stars upon it, which, 

 being accompanied by figures of men and by hieroglyphical symbols, 

 appeared to have been distinguished on account of some particular 

 interest attached to them ; and concluding from their positions with 

 respect to the nearest zodiacal signs that they must represent Fomal- 

 haut, Antares, Arcturus, and |3 Pegasi, he first verified them by the 

 near agreement of their measured distances from each other on the 

 planisphere with the distances obtained by computation from their 

 known angular distances in the heavens ; then computing the angles of 

 the triangle formed by two of the stars and the centre, or pole, of the 

 planisphere, and also the angles of the triangle in the heavens between 

 the arcs joining the two stars and the pole of the ecliptic in 1750, he 

 found, by comparison, the latitude and longitude of the centre of the 

 planisphere with respect to the positions of the ecliptic and the equi- 

 noctial point for that year. The position of the centre, thus found, is 

 that which the pole of the world must have occupied about the year 

 716 B.C. ; and he thence concludes that the planisphere presents the 

 state of the heavens at the latter epoch. M. Biot afterwards calcu- 

 lated for that epoch the places of the principal stars, and determined 

 their situations on a plane by the rules of the projection supposed, as 

 above mentioned, to have been used in constructing the Kgyptian 

 monument : on comparing the map so formed with an exact copy of 

 the planisphere, he found the stars to fall upon or near the figures to 

 which they were presumed : o belong. Thus the stars of Ursa Minor 



