CONTENTS xix 



CHAP. PAGE 



X. The slowness and steadiness of the Comet could not be 



accounted for on this assumption, nor its general behaviour and 

 shape 281 



XI. We must look for some other explanation. Now Comets, it 

 must be premised, appear in all quarters of the sky. Whatever 

 the divisions of them made by the Greeks, they are all of one 

 origin. Some of the ancients thought they were due to the 

 union of two planets ........ 283 



XII. Again the facts do not square. Comets and planets appear 

 simultaneously. A conjunction is momentary, a Comet lasts six 

 months sometimes. The planets do not pass much beyond the 

 ecliptic, but Comets appear in every quarter of the sky. And 



there are other objections ....... 284 



XIII. Artemidorus thinks the firmament is solid and has openings 

 for stars. Comets are casual planets, or formed by conjunctions 



of them. His account is a tissue of barefaced falsehoods . . 286 



XIV. How would a solid firmament be supported ? No feasible 

 explanation can be offered. Besides, the number of stars is so 

 great and they may all be " wanderers " if an indefinite 

 number is that there must be innumerable conjunctions of them, 



i.e. Comets. But, as a matter of fact, Comets are rare . . 287 



XV. Again the huge Comets of the times of Demetrius and Attalus 

 would require scores of planetary conjunctions to form them . 288 



XVI. Ephorus, a mere chronicler, who takes this view, has nothing 

 to support him. He tries, like others of his set, to embellish his 

 work by narrating marvels. Why did he not tell us what the 

 two stars were into which the Comet resolved itself, as he alleges 



it did ? 289 



XVII. Apollonius of Myndus holds the Comet to be a true star 

 (planet) with an erratic course, visible only when it approaches 



the lower part of its orbit. Different colours of Comets . . 290 



XVIII. But Comets do not wax and wane as they approach and 

 recede like planets. Nor do their orbits lie within the ecliptic. 

 Besides, we can see through a Comet but not through a true star 

 (planet) . . .291 



XIX. Zeno the Stoic thinks the light of converging stars gives the 

 appearance of a longer star. Others hold modified forms of the 

 same opinion or analogous views 291 



XX. Most of the Stoics hold Comets to be evanescent, and attribute 



them to friction of the air. Various phenomena are analogous . 292 

 XXL Their methods of accounting for varieties of orbits in Comets . 293 



XXII. I do not agree with any School. Reasons .... 295 



XXIII. Further arguments showing difference between fires and 

 Comets 295 



XXIV. There may be many stars in the universe whose paths have 

 not been traced : Comets are such. No satisfactory explanation 



has been given of the mind, but its existence is not doubted . 297 



XXV. Comets are not yet fully understood. Many things are in the 

 same category. A future age will be amazed at our ignorance of 



such matters ......... 298 



