Astronomical and Nautical Collections. 31 1 



REMARKS. 



No. Year. 



(15.) 1682. This orbit of Halley's comet deserved to be inserted, because it 

 rests wholly on Cassinis observations, while all the rest are 

 derived from FlamsteacTs. Hist. Ac. Par. 1759, p. 162. 



55. 1743. In these elements, the first observation of Grischow has been 



employed with the rest. The observations of this comet 

 cannot be represented by a parabola, and inaccurate as they 

 are, they still appear to indicate an ellipticity of the orbit. 

 In Lacaille's elements the longitude of the node should be 2s. 

 18° 21' 15". 



56. 1743. For D we must certainly read R : and the angle between the 



perihelium and the node must consequently be 3s. 28° 42 / 

 33". Astr. Nachr. N. 48. p. 494. 



J24. 1822. These improved orbits of Gambart and Nicollet are found in 

 the Connaissance des T. 1826. p. 219, 278, with the observa- 

 tions made at Marseilles, and at Paris. Gambart computes 

 from the mean equinox of 12th May, 1822. 



125. 1822. Rumker has deduced both his orbits from the observations 

 made by himself at Paramatta up to the 11th November. I 

 have assumed the longitude of Paramatta 9h. 54 m 44*. Encke 

 in his last orbit has comprehended both the European obser- 

 vations and those of Rumker : so that these elements seem 

 to be preferable to any other. Gambart computed from the 

 mean equinox of 12th July: Rumker 1 Jan. and Encke 25 

 Oct. 1822. Connaiss. des T. 1826. Astr. Nachr. II. N. 

 37. p. 207.. . HI. N. 55, p. 107. . . 



Many astronomers have omitted, after the most accurate determination 

 of the orbit of a comet, to mention the date of the place of the equinoctial 

 point, from which they compute the longitudes. For the sake of uniformity, 

 and in order to avoid all uncertainty and confusion, it is much to be de- 

 sired, that all computers would employ the place of the equinox for Ja- 

 nuary, in the year to which the perihelium of the comet belongs. 



%* Professor Schumacher, the ingenious editor of these Essays, 

 requests his Correspondents to observe, that his usual residence is at 

 Alton a, and that Professor Schumacher, of Copenhagen, is an anatomist, 

 and not an astronomer. 



