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On the Different Methods of Constructing a Catalogue of Fixed Stars, 

 By J. Pond, Esq. F.R.S. Astronomer Royal. Read May 21, 1818. 

 [Phil. Trans. 1818,;?. 405.] 



The method hitherto adopted in the Royal Observatory for con- 

 structing a catalogue of stars, either in declination or right ascension, 

 has been to take some one star as a point of departure, and thus to 

 determine the position of the rest by direct comparison. The decli- 

 nations were determined by direct comparison with y Draconis, and 

 a Aquilse was chosen as the common term of comparison in right 

 ascension. In observations with the transit instrument, this mode of 

 proceeding is highly objectionable ; for every result is subject to a 

 double error, that committed in the observation of a Aquilse, and that 

 in the observation of the star itself. Besides which, if the observation 

 of a Aquilae be omitted, then the other observations become useless. 

 Hence, although extreme accuracy was ultimately thus obtained by 

 the late Astronomer Royal, the method was tedious and objection- 

 able. 



The method which Mr. Pond proposes to substitute, and which he 

 describes in this paper, has the advantage of affording, in a single 

 year, a catalogue equally accurate with one formerly obtained in three, 

 and equally applicable to the mural circle and transit instrument. No- 

 particular star is in either case assumed as a point of departure in 

 preference to the rest. On the contrary, every star is in its turn as- 

 sumed as a point of reference to the others. It is thus endeavoured, 

 in the first instance, to establish their relative distances from each 

 other, or from the equator or meridian, leaving the choice and deter- 

 mination of some common point of departure as a subject for future 

 consideration. The principles of proceeding applicable to both in- 

 struments are then detailed at length, and the striking coincidence 

 of the author's catalogue, and that of the late Dr. Maskelyne, ad- 

 verted to. 



In respect to the accuracy of the results afforded by the new transit 

 instrument, Mr. Pond thinks that 120 observations enable him to 

 define the place of a fixed star to one tenth of a second of a degree. 



A Description of the Teeth of the Detphinus Gangeticus. By Sir 

 Everard Home, Bart. V.P.R.S. Read June 4, 1818, [Phil. Trans. 

 1818, p. 417.] 



In the 7th volume of the Asiatic Researches, published in 1781, 

 Dr. Roxburgh describes the Delphinus Gangeticus, but gives a very 

 imperfect account of its teeth ; nor is any detailed account of them 

 given in any other work. As the jaws and teeth of this species of 

 Delphinus form its most remarkable character, Sir Everard thinks the 

 subject of sufficient interest to the comparative anatomist and geolo- 

 gist, to be laid before this Society. 



These teeth, as in the whole tribe, generally have the rudiments in 

 the cfuins, from which the teeth grow in both directions ; upward- 



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