Comets have been alternately regarded with terror and with welcome in the popular mind. The appearance of Halley's comet in 1456, just as the Turks had become masters of Constanti nople, and threatened an advance into Europe, was regarded by Christendom with a supersti tious dread, and to the Ave Maria was added the prayer: "Lord, save us from the devil, the Turk. and the comet." At Constantinople, the occurrence of a lunar eclipse at the same time, increased the portentousness of the event. The discoveries of science as to the magnitude of the space tilled by their bodies and their prodigious velocity, together with the confessed impossi bility of always predicting their approach, pro (bleed fears of another kind, which have some times been, especially in France, extravagantly exaggerated in the public mind. The ground lessness of such alarms, from the extreme im probability of collision with the nucleus, the probable innocuousness of a contact with the extremely attenuated surrounding matter, and, possibly, to the greater part of the world. of a collision with the nucleus itself, will be suffi ciently evident from what has been said above.
It is probable that already on many occasions some of the attenuated vapor in the tail of comets must have conic within the earth's at traction. and been absorbed in its atmosphere. Whether the effect is deleterious or salubrious, or whether it has any perceptible influence at all, is only matter of speculation. The salubrity of cometary influence was at one time a popular idea; and the vintages of 1811 and 1858 were favorable seasons, whose produce was formerly advertised as the comet wines. It is scarcely worth while, however, to follow further specula tion on these subjects. Consult: Guillemin, The World of Comets, trans. by Glaisher (London, 1881) ; Zilllner. Urber dig Natur der Kometen (Leipzig, 1883) : Mareuse, L'elwr dir physisehe Besehaffenhcit der Konetrn (Berlin, 1884) : Ball, In the Starry Realm (London. 1892) ; Galle, rerzeiehnis der Elcmente der bishcr bc rechneten Kometenbabnen his zum Jahee 1894 (Leipzig, 1894); Lynn, Remarkable Comets (Loudon, 1899).