m 



Rev. T. J. Hussev's Catalogue of Comets. 



in the experiment to do. Indeed, when x increases still 

 further, that is, when the eye is withdrawn from the prism to 

 a distance greater than the length of the incident path, that 

 is, greater than the distance of the prism from the two near 

 luminous origins, the curve begins to tend the other way, 

 though much more slowly ; but the experiments of Mr. Potter 

 do not seem to have been made at so great a distance from 

 the prism, and therefore the phenomenon, which he observed, 

 appears to be explained by the undulatory theory. 

 Dublin Observatory, Feb. 12, 1833. 



XXX. A Catalogue of Comets. By the Rev. T. J. Hussey, A. M. 

 Recto?- of' Hayes, Kent*. 



TN a Catalogue of Comets, more is required than a compi- 

 -*- lation of those only of which modern industry has calcu- 

 lated the elements. In proportion as the periodic times of 

 a greater number are ascertained, is it requisite to search in 

 the pages of history for intimations of their former appear- 

 ance ; but this is an undertaking of no ordinary difficulty, as 

 regards both its nature and extent. To sift the details of the 

 journalist of a convent, or the annalist of a kingdom, or the 

 meagre narrative which is dignified with the name of history, 

 is a task sufficiently irksome, and too often fruitless ; — when no 

 acuteness of discrimination can positively decide between the 

 notice of a meteor and the record of a comet ; can reduce the 

 exaggerations of superstitious terror to their true proportions, 

 and separate the visions of the mystic, or the fictions of the 

 astrologer, from the ill-understood and more imperfectly re- 

 gistered phenomena of nature. So far as it is possible this 

 has been executed by Pingre; and if he has added nothing 

 to the theory of comets, his history of them is an unrivalled 

 monument of industry, fidelity and judgement. This opinion 

 is the result of a close and extensive examination and verifi- 

 cation of his work, which has served as the foundation of the 

 present Catalogue. 



The best Catalogue of Comets of which the elements have 

 been computed, is probably that contained in the third volume 

 of Delambre's Astronomy! : this has been extended from va- 

 rious sources, which must be familiar to every scientific reader, 

 and brought up to the present year ; thus, it is to be hoped, 

 supplying a desideratum in Astronomy. 



* Communicated by the Author, 

 f Olbers's Abhandlung, published at Weimar in 1797, contained a short 

 Catalogue of 89 Comets which had been observed previously to that year. 



