The notices of comets given by our old historical writers and diarists have no scientific value. They are only worthy of notice, as shewing the views entertained regarding comets by the people of an early and unenlightened age. The real nature of these strangers of the sky is not yet ascertained; but we have at least come to know some of the laws by which they are governed; above all, we know the great fact, that they are obedient to law. To our ancestors, they appeared in a very different light--as menacing messengers, sent for special reasons, ‘importing change of times and states.’ Some of the views expressed regarding them are sufficiently remarkable to be worthy of preservation. The comet of 1577 was a very noted one, seen over Europe and Asia, also in Peru, and well observed by Tycho Brahé. Its tail, according to the description of the Danish astronomer, extended over 22 degrees. Such was the real space described by James Melville as an ell and a half! This comet passed its perihelion on the 26th of October in the year mentioned, and was visible, as we see, for a considerable portion of the winter. The date here given for its first appearance in Scotland is from the _Aberdeen Chronicle_. The most noted comet at this time recent, was one called in Scotland the _Fiery Besom_, which has been set down at various dates by English and Scottish historians, but was undoubtedly identical with that so well known in the history of astronomy as having appeared in 1556. John Knox tells us that it presented itself during the winter which he spent in Scotland before his last return to France--a time when the doctrines of the Reformation stood in the most perilous circumstances in both England and Scotland, and men’s minds were consequently in a state of great excitement. Sir James Balfour speaks of it as having portended change not only in government, but in religion, and Knox takes care to note--‘_Soon after_, Christian, king of Denmark, died, and war raise betwixt Scotland and England, &c.’ Modern astronomers believe this comet to be the same with one which alarmed Europe in 1264, and Professor Hind is predicting that it must speedily revisit our skies, at the very time when these sheets are passing through the press. It is a curious consideration, that a heavenly body which left the confines of our sphere on its stated journey when Cranmer stood at the stake in Oxford, should next come amongst us when we are busy with such an affair (for example) as the laying of the electric telegraph across the Atlantic. * * * * * [Sidenote: DEC. 18. 1577.]