400 OF THE NEW PtANET,

antiquity the glory which they have lost by .theirweakness. They were, most probably, ac-quainted with the varying obliquity of the eclip-tic, and having discovered this epocha by cal-culation, pretended that it was derived fromreal observations.

Some, however, are of a contrary opinion jand from the uncertainty of ancient observa-tions, are disposed to believe, that the obliquityof the ecliptic has been always the same. Butin this they are certainly mistaken; for besidesthe apparent decrease of this angle, which hasbeen observed by almost every astronomer sincethe time of Hipparchus, the variation of latitudein the .fixed stars is such as could arise from noother cause. Ptolemy tells us expressly that hedetermined the obliquity, for several years toge-ther, to be 23 degrees 51 minutes, and it is nowknown to be 3:3 degrees 28 minutes, which ap-pears to be too great a difference to be attri-buted to any defect in his observations. Butindependent of ancient testimonies, the atten-tion which has been bestowed upon this subjectfor near a century past, has enabled us to decidewith certainty that the diminution is real, andaccording to a certain law. • - •

M. Euler, and other mathematicians, haveendeavoured to strew, that this effect is producedby the attraction of the planets; but as theprincipks which they have employed are too.

abstruse