40 PHILOSOPHICAL TRANSACTIONS. [aNNO 1665. 



He finds the matter of comets to be in the asther itself ; and that the planets 

 emit their exhalations, and have their atmospheres like our earth. He affirms 

 that the sun alone may cast out so much matter at any time in one year, as that 

 thence shall be produced not one or two comets, equalling the moon in diame- 

 ter, but very many ; which if so, what contribution may not be expected from 

 the other planets.* 



He conceives that all comets respect the sun as their centre as planets do, 

 making them a kind of spurious planets that emulate the true ones in their 

 motion almost in all things. 



The train, according to him, is only the beams of the sun falling on the 

 head of the comet, and passing through the same, refracted and reflected. 



Whether the same comets return again, as the spots in the sun ? and. Whe- 

 ther in the time of great conjunctions they are more easily generated ? and. 

 Whether they can be certainly foretold ? with several other inquiries, he refers 

 for to his great work. 



As to prognostications, he complains, that men inquire more what comets 

 signify than what they are, or how they are generated and moved ; professing 

 himself to be of the opinion of those who would have comets rather admired 

 than feared ; there appearing indeed no cogent reason, why the Author of Na- 

 ture may not intend them rather as monitors of his glory and greatness than 

 of his anger or displeasure; especially seeing that some very diligent men 

 (among whom is Gemma Frisius) take notice of as great a number of good as 

 bad events consequent to comets. 



Some animadversions have been made on this work by M. Auzout, in a let- 

 ter to M. Petit ; in which he conceives that this prodromus contains some 

 mistakes, which he particularises. 



Of the Mundus Suhterraneus of Athanasius Kircher.'\ N" 6, p. I09. 



This paper contains a long and tedious account of this work, after the man- 

 ner of a modern review of it, enumerating all the particulars of the contents : 

 an account now no longer either curious or useful. 



* It is curious, and not unprofitable, sometimes to observe the strange whims and puerile notions 

 which some of tlie greatest men have formed in the early periods of certain natural and scientific dis- 

 coveries. 



t Athanasius Kircher, or Kirker, a noted philosopher, W3s born at Fulda in 1601. He entered 

 into the society of Jesuits in 10 18, and taught philosophy, mathematics, and the oriental languages in 

 tlie university of Wirtsburg, till tlie year 1^3 J. He was afterwards called to Rome, where he 

 taught mathematics in the Roman college, &nd died in 168O, being the 80th year of his age. — Kirker 

 collected a rich cabinet of machines and antiquities j and the quantity of his works is immense. 



