With reference to its appearance in the year 1456, when it was of "vivid brightness," and had a tail of 60° in length, Admiral Smyth says,[204] "To its malign influence were imputed the rapid successes of Mahomet II., which then threatened all Christendom. The general alarm was greatly aggravated by the conduct of Pope Callixtus III., who, though otherwise a man of abilities, was a poor astronomer; for that pontiff daily ordered the church bells to be rung at noon-tide, extra _Ave-Marias_ to be repeated, and a special protest and excommunication was composed, exorcising equally the Devil, the Turks, and the comet." With reference to this story, Mr. G. F. Chambers points out[205] that it is probably based on a passage in Platina's _Vitæ Pontificum_. But in this passage there is no mention made of excommunication or exorcism, so that the story, which has long been current, is probably mythical. In confirmation of this view, the Rev. W. F. Rigge has shown conclusively[206] that no bull was ever issued by Pope Callixtus III. containing a reference to _any_ comet. The story would therefore seem to be absolutely without foundation, and should be consigned to the limbo of all such baseless myths.
With reference to the appearance of Halley's comet, at his last return in 1835, Sir John Herschel, who observed it at the Cape of Good Hope, says--
"Among the innumerable stars of all magnitudes, from the ninth downwards, which at various times were seen through it, and some extremely near to the nucleus (though not _exactly on it_) there never appeared the least ground for presuming any extinction of their light in traversing it. Very minute stars indeed, on entering its brightest portions, were obliterated, as they would have been by an equal illumination of the field of view; but stars which before their entry appeared bright enough to bear that degree of illumination, were in no case, so far as I could judge, affected to a greater extent than they would have been by so much lamp-light artificially introduced."[207]
It is computed by Prof. J. Holetschak that, early in October, 1909, Halley's comet should have the brightness of a star of about 14-1/2 magnitude.[208] It should then--if not detected before--be discoverable with some of the large telescopes now available.