COMETS. 9i> 



concealed from our observation, and must always remain so, 

 unless new and unexpected disturbing causes come into play. 

 These cosmical relations involuntarily remind us of nearly 

 similar conditions in the intellectual world, where, in the do- 

 main of deep research into the mysteries and the primeval 

 creative forces of nature, there are regions similarly turned 

 away from us, and apparently unattainable, of which only a 

 narrow margin has revealed itself, for thousands of years, toi 

 the human mind, appearing, from time to time, either glim- 

 mering in true or delusive hght. We have hitherto consid- 

 ered the primary planets, their satellites, and the concentric 

 rings which belong to one, at least, of the outermost planets, 

 as products of tangential force, and as closely connected to- 

 gether by mutual attraction ; it therefore now only remains 

 lor us to speak of the unnumbered host of comets which con- 

 stitute a portion of the cosmical bodies revolving in independ- 

 ent orbits round the Sun. If we assume an equable distribu- 

 tion of their orbits, and the limits of their perihelia, or greatest 

 proximities to the Sun, and the possibility of their remaining 

 invisible to the inhabitants of the Earth, and base our esti- 

 mates on the rules of the calculus of probabilities, we shall 

 obtain as the result an amount of myriads perfectly astonish- 

 ing. Kepler, with his usual animation of expression, said that 

 there were more comets in the regions of space than fishes in 

 the depths of the ocean. As yet, however, there are scarcely 

 one hundred and fifty whose paths have been calculated, if 

 we may assume at six or seven hundred the number of comets 

 whose appearance and passage through known constellations 

 have been ascertained by more or less precise observations. 

 While the so-called classical nations of the West, the Greeks 

 and Romans, although they may occasionally have indicated 

 the position in which a comet first appeared, never afford any 

 information regarding its apparent path, the copious literature 

 of the Chinese (who observed nature carefully, and recorded 

 with accuracy what they saw) contains circumstantial notices 

 of the constellations through which each comet was observed 

 to pass. These notices go back to more than five hundred 

 years before the Christian era, and many of them are still 

 found to be of value in astronomical observations. =^ 



* The first comets of whose orbits we have any knowledge, and 

 which were calculated from Chinese observations, are those of 240 (un- 

 der Gordian III.), 539 (under Justinian), 56-5, 568, 574, 837, 1337, and 

 1385. See John Russell Hind, in Schiini., Astron. Nachr., 1843, No. 498. 

 While ihe comet of 837 (which, a^cordin^ to Du Sejour, continued dur- 



