I.ET. XXII. SON AND MOON. 377

unfolded the theory of gravitation, and me-chanics have been brought in to give their assist-ance to philosophy, that we have had a just ideaof the construction of the universe; and thougheclipses might have been computed independentof this knowledge, yet the calculations must havebeen far less exact than they are at present.

The accounts which are to be found in manyof the early historians, concerning the predictionof eclipses, by Thales, Anaxagoras, and others,who lived long before the commencement ofthe Christian æra, are only to be understood ofsome of the most remarkable of these phæno-mena, which a gross calculation might deter-mine, sufficiently near the truth, to excite theadmiration of an uninformed age. There aremany elements that are used in the exact com-putation of solar eclipses in particular, whichastronomers, in a less advanced state of thescience, must have been totally unacquaintedwith; and an the moderns, by these means, haverendered their calculations far more accurateand precise, it affords a convincing proof, evento the most illiterate, that the principles fromwhich such a perfect knowledge of the heavenlymotions is derived, must be just and undeniable.

To enter into a popular explanation of all theprinciples of this doctrine, would be no easy talk.I shall therefore only attempt to give you a ge-neral idea of the subject, and to shew you, with-out