ASTRONOMY. 



By Prof. Edavaed S. Holden, 



INTRODUCTION. 



As the space available for the record of astronomical i)rogress is com- 

 paratively small, the accounts here given must necessarily be the biirest 

 summaries, whose chief end is to call attention to work which has been 

 done, in order that a reference may be made to more extended x)apers if 

 desired. . At the same time it is clearly impossible to give a specific ref- 

 erence to each of the papers consulted. 



For such bibliograiihic information the reader is once for all referred 

 to Darboux et Houel's Bulletin des Sciences Mafhematiqucs et Astrono- 

 miques (monthly, Paris), to Nature (weekly, London), to Science (weekly, 

 New York), to the Observatory (monthly, London), and to other standard 

 journals. Free use has been made of reviews by writers in these and 

 other periodicals, i)articularly of the Becord of Astronomy, ])iib\ishedhy 

 Dr. J. L. E. Dreyee in the Scieutilic Proceedings of the Eoyal Dublin 

 Society. 



NEBULA AND CLUSTERS. 



The Earl of EosSE has published Parts 1 and 2 (0^ to 14^ R.A.) of 

 the " Observations of Nebuloe and Clusters of Stars made with the six- 

 foot and three-foot reflectors at Birr Castle from the year 1848 up to 

 about the year 1878" (Trans. R. Dublin Soc, Vol. II). This publication 

 (of which the third part, comprising the last ten hours of R.A., is in 

 the press) embodies all the work done on nebulie since the erection of 

 the six-foot telescope in 1845. In 1850 and 1861 abstracts of the observ- 

 ations on more interesting objects appeared in the Philosophical Trans- 

 actions, but all these abstracts are given over again in the new publica- 

 tion, with the sole exception of the copperplate engravings, to which, 

 however, in all cases references are made in the text. Though even now 

 not every single note in the observing ledgers is published, nothing has 

 been supjjressed which can be of the slightest value or importance. 

 The observations are given in the observer's own words, and the notes 

 which were added by Mr. Dreyer while arranging the work for pub- 

 lication are easily distinguished by being inclosed in brackets. These 

 notes deal especially with questions of identiiication, and nearly all the new 



nebulae which were found at Birr Castle in the course of years and which 



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