PROVISIONAL THEORY 



OF 



L E D A. 



The little planet, that forms the subject of the present memoir, was dis- 

 covered at the Imperial Observatory of Paris on the evening of the 21 st 

 of January 1856 by Mons. Chacornac. Its diameter is stated]' to be only 

 about 5 Sweedish miles* (= 33 English Miles or 53 Cliilometres), and its 

 brightness, when in opposition, is somewhat inferior to that of a star of the 

 10' h magnitude. Immediately after the discovery the elements of its orbit 

 were approximately determined by the late M:r Pape of Altona. During 

 the earlier months of 1856 it was frequently observed at Berlin, as also 

 at Greenwich, Cambridge, Kremsmiinster, Grottingen, Liverpool and other 

 places, and from these observations a new set of elements was calculated 

 by Mr Lowy and published in the Memoirs of the Imperial Academy of 

 Wien. (vol. xxiv) 



The opposition of 1857 passed without affording any addition to the 

 stock of observations; for the planet having at that time a considerable 

 south declination, its smallness and low elevation rendered it a difficult ob- 

 ject even for the most powerful instuments. The number of good observa- 

 tions obtained during the first five months of 1856 Avas however very con- 

 siderable, and, by a careful discussion of these, H:r Alle was enabled to 

 deduce the elements hitherto used in calculating the ephemerides of the pla- 

 net, that have regularly appeared in the Nautical Almanac and Berliner 

 Jahrbuch, and which I have employed as the basis of the following theory. 

 H:r Alle's memoire on this subject was published by the Imperial Academy 

 of Wien 1858. 



It would however be unreasonable to expect that a set of elements de- 

 duced from only four months' observation of a planet whose period amounts 



Lindhagen, Astronomiens Grander, p. 520. 



