zn the Axis and Poles of ihe Karth. 3 r 9 



component parts, occafioned by the acccffion of heat ; to the 

 fokition and decompofuion of thele fubdanccs fo different 

 in their nature, evaporated from the furtace of the earth, whe- 

 ther land or water, which is filled with animal and vegetable 

 bodies ; and to tliefe vapours being in part conveyed into the 

 atmofphcre, and there converted into otber matters, and being 

 again font back to it in the fo:m of fertilizing; mnifture. 



in the lalt place, all our obfervations have hitherto ftown 

 that without the globe of the earth there is no power capable 

 of producing iuch irregularities in its poles and its axis. 



It was long believed indeed that comets were capable of 

 producing fuch revolutions. Who kno\vs, faid fome, whe- 

 ther one of thefe bodies niav not have approached too near to 

 our earth; and, being furniflicd with too great attraftive 

 power, may have deranged its axis or its pole, or dragged its 

 train over us; and, fetting every thing on fire, may have laid 

 wafie Tea and land, altered the eartli's centre of gravity, and 

 occafioned a general devaftalion ? 



But ourprefent more accurate knowledge of the orbits and 

 nature of thefe celeftial bodies will never adnjit of any fuppo- 

 lition of this kind. It is known from certain experience, 

 and the confcquences thence deduced, that thefe mafies have 

 vc-rv little fpecific gravity, and therefore nuilt pollefs a verv 

 weak attractive power. According to every appearance, thev 

 feem to be compoi'ed of minute moleculae mixed with the 

 fine ethereal matter of light, and their trains are only highly 

 lubtile luminous and tranibarent fabftances; fo that we have 

 very little to apprehend frmn either of them. 



No hiftorian worthy of credit ever makes mention of the 

 difaftrous efi'ects of comets on our earth; and mankind are 

 now too enlightened to be led into error by what the pr.eju- 

 dice, fuperl'tition, and Ignorance of former times have handed 

 down to us on this fubjcft. 



Even in modern times comets have pafled very near our 

 earth, without produc'ng any remarkable phrenoniena, 

 either in regard to the atmofphere or the common courfe of 

 the weather; and much lefs were the poles or the axis of the 

 earth any way affcfted by their apnroach; otherwii'e fomc 

 traces of it would not have efcaped the refearches of the mo- 

 dern aftronomers. On the other hand we know, bv expe- 

 rience, that comets which have palled near to our earth, or 

 the other planets, in their way to tlic fun, have lutfered fome 

 pcrlLubatiou in their orbits by the attractive power of tlie 

 latter. 



I will not however aflert that our earth, before it was 

 completely formed and rendered habitable, and before every 



part 



