60 CELESTIAL, ATMOSPHEEIC, AND 



metalliferous substances, except gold, are produced, contain 

 some earthy substance. Aristotle's explanation of the pro- 

 duction of metallic substances does not show how the gold, 

 &c., was supposed to exist in the vaporous exhalation, but 

 his explanation resembles, in a crude way, one of the modern 

 views of the formation of metalliferous veins by the deposition 

 of metalliferous substances from very hot steam ascending 

 through fissures in the crust of the Earth. 



At the end of Meteorol. iii. c. 7, Aristotle says that each 

 kind of mineral substance should be described separately. 

 It is said that the alchemists used to refer to a work dealing 

 with the transmutation of metals, and that they assigned 

 this work to Aristotle. It seems to be very unlikely that 

 Aristotle wrote a separate work on metals or mineral sub- 

 stances. There appears to be nothing in Olympiodorus to 

 show that such a work was written. Theophrastus wrote a 

 separate work, entitled O71 Stones, in which he practically 

 accepts Aristotle's division of mineral substances and their 

 production from exhalations, but the rest of the work 

 suggests very little that can be traced to Aristotle, who, 

 moreover, is not even mentioned by name. 



Having described Aristotle's explanations of many celes- 

 tial, atmospheric, and terrestrial phenomena, it remains to 

 describe the most interesting parts of his work on these 

 phenomena, viz., his numerous records of the phenomena 

 themselves. In what follows, the records of celestial 

 phenomena will be described first, then the records of 

 atmospheric, and, finally, those of terrestrial phenomena. 



In the year B.C. 373, Aristotle saw a great comet which 

 appeared in the west on a clear, frosty evening in winter, 

 when Aristaeus [Asteus] was archon. It set before the sun 

 on the first evening, but was well seen on the next evening, 

 although it set quickly. Its tail extended as far as the Belt 

 of Orion, and there faded away. This tail appeared as a 

 well-defined track, whence it was called a *' road."* 



According to von Humboldt, t this comet was believed by 

 von Boguslawski to have been the same as the comets of 1843, 

 1695, 1548, and 1401, with a period of one hundred and 

 forty-seven years. Von Boguslawski, in fact, called that of 

 1843 the Comet of Aristotle, which he traced back to the 

 year B.C. 371. It may be mentioned that the comet of 1843 

 was very brilliant. 



=•'■ Meteorol. i. c. 6, ss. B and 10. 



f Cosmos, Bohn's Library, 1849-1868, vol. ii. p. 526, and vol. iv. p. 541. 



