An Irish Corpus Astronomiae

Our author begins with chronology, passes on to physics and agriculture, devotes the bulk of his book to astrology and ends with a perfunctory treatment of the application of astrology to medical theory and practice: it will be most convenient to follow this order in giving a short sketch of the progress of those branches of science before his time, and the conditions under which the work was written and translated. The daily life of the farmer and the sailor had from the...
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Our author begins with chronology, passes on to physics and agriculture, devotes the bulk of his book to astrology and ends with a perfunctory treatment of the application of astrology to medical theory and practice: it will be most convenient to follow this order in giving a short sketch of the progress of those branches of science before his time, and the conditions under which the work was written and translated.

The daily life of the farmer and the sailor had from the earliest times necessitated some elementary knowledge of astronomy so far as concerned the points of the compass, the revolution of the seasons and the phases of the moon: the necessities of civil government and historical records of even a meager kind demanded greater precision in chronological calculations, which the rise of scientific curiosity with regard to the movements of the sun, moon and planets, and the revolution of the stars, afforded the means of fixing. The labors of astronomers and mathematicians in Babylon, Egypt and Greece had brought these calculations to a reasonable degree of precision by the first century B.C.: the length of the solar year had been approximately determined; the division of time into months according to the phases of the moon had been accommodated to the more accurate division based upon the path of the sun among the signs of the zodiac; and some attempt had been made to harmonize the various methods of reckoning time which were in vogue in different countries and apply the results of these researches to the formation of canons of historical chronology. These studies were pursued by the mathematicians and astronomers of Alexandria with marked success under the enlightened patronage of the Ptolemies: Julius Caesar made use of their labors in the reformation of the Roman Calendar which, under the combined influences, of ignorance and sacerdotal fraud, had fallen into a state of portentous confusion. When he employed the Alexandrian, astronomer Sosigenes upon the task it was found impossible to bring the civil into conformity with the astronomical reckoning by any means less drastic than the addition of 67 days to the current year. The reforms of Sosigenes adopted on the 1st of January 45 B.C. remained in use until Pope Gregory XIII., employing the more accurate calculations, then possible, introduced in 1582 the calendar still in use.

The application of more accurate chronological researches to the science of history was introduced to the Roman world by a contemporary of Caesar, M. Terentius Varro, who did little more than adopt the fruit of the labors of Alexandrian scholars. His accurate and laborious application of scientific methods of research to the history of Rome and of Latin Literature marks an epoch in chronological studies; his results (though his historical and chronological treatises exist only in fragments) were adopted by succeeding writers who did not always acknowledge the debt with the frankness with which S. Augustine confesses to a similar obligation in the sphere of Roman religion.