From a photograph taken, on August 11th, 1907, by Dr. Max Wolf, at the Astrophysical Observatory, Heidelberg. The instrument used was a 28-inch reflecting telescope, and the time of exposure was fifteen minutes. As the telescope was guided to follow the moving comet, the stars have imprinted themselves upon the photographic plate as short trails. This is clearly the opposite to what is depicted on Plate XIII. (Page 258)] CHAPTER XX REMARKABLE COMETS If eclipses were a cause of terror in past ages, comets appear to have been doubly so. Their much longer continuance in the sight of men had no doubt something to say to this, and also the fact that they arrived without warning; it not being then possible to give even a rough prediction of their return, as in the case of eclipses. As both these phenomena were occasional, and out of the ordinary course of things, they drew exceptional attention as unusual events always do; for it must be allowed that quite as wonderful things exist, but they pass unnoticed merely because men have grown accustomed to them. For some reason the ancients elected to class comets along with meteors, the aurora borealis, and other phenomena of the atmosphere, rather than with the planets and the bodies of the spaces beyond. The sudden appearance of these objects led them to be regarded as signs sent by the gods to announce remarkable events, chief among these being the deaths of monarchs. Shakespeare has reminded us of this in those celebrated lines in _Julius Cæsar_:-- "When beggars die there are no comets seen, The heavens themselves blaze forth the death of princes." Numbed by fear, the men of old blindly accepted these presages of fate; and did not too closely question whether the threatened danger was to their own nation or to some other, to their ruler or to his enemy. Now and then, as in the case of the Roman Emperor Vespasian, there was a cynical attempt to apply some reasoning to the portent. That emperor, in alluding to the comet of A.D. 79, is reported to have said: "This hairy star does not concern me; it menaces rather the King of the Parthians, for he is hairy and I am bald." Vespasian, all the same, died shortly afterwards! Pliny, in his natural history, gives several instances of the terrible significance which the ancients attached to comets. "A comet," he says, "is ordinarily a very fearful star; it announces no small effusion of blood. We have seen an example of this during the civil commotion of Octavius." A very brilliant comet appeared in 371 B.C., and about the same time an earthquake caused Helicè and Bura, two towns in Achaia, to be swallowed up by the sea. The following remark made by Seneca concerning it shows that the ancients did not consider comets merely as precursors, but even as actual _causes_ of fatal events: "This comet, so anxiously observed by every one, _because of the great catastrophe which it produced as soon as it appeared_, the submersion of Bura and Helicè."