210 Hi it or If of Astronomy for tJw Year 1S03. 



I have calculated some hundreds of the sun's altitudes 

 observed in England and France, for several vears back, be- 

 fore and alter the ecjuinox, and have deduced from them 

 the sun's right ascension, and consequently that of the stars 

 which had been compared with him. I have found that it 

 is necessary to add 5 ' to the positions of the stars which 

 Dr. Maskelvne gave us as being certain to a second, and 

 ■which all astronomers employed with the greatest security : 

 but perceiving that observations made at the distance of 40° 

 from the zenith and at 60*^ gave right ascensions which 

 differed sometimes 15", I concluded that there were errors 

 of division of b" in the interval of 20 degrees : it will there- 

 fore be necessary to recur to the whole circle, to verify the 

 nuiral quadrants employed at Paris and at Greenwich. 



1 was at first surprised to find errors of lO" and then of 

 20" in the right ascensions ; but I thought them of less 

 consequence when I saw that from 42 to 45 degrees they 

 were lO", and that from 54 to bQ they amounted to 20". 

 Tlie medium, therefore, between results very different is 

 found to be the same, because the altitudes correspond at 

 the two seasons, and the sum of the small errors compen- 

 sates for that of the great. 



To remedy this inconvenience in the divisions of the 

 mural quadrant, M. Dclambre this year observed the sun 

 for two months, partly before and partly after the autumnal 

 equinox, with a multiplying circle, and by 300 observations 

 he had places of the sun independent of the stars. But a 

 second in the refraction, or in the height of the pole, may 

 occasion all the uncertainty : it will, however, be removed a6 

 the next equinox. 



Picard and La Hire in the seventeenth century made the 

 first correct observations for accomplishing this end, and 

 the French in the present century will have made the last 

 to attain it completely. 



Hcrschel asserts that the stars called Castor y of the. 

 Lion, and several other double stars very near to eaclj 

 other, turn round in periods of some centuries. M. Tries- 

 necker is not of opinion with M. Flauguergues, that in the 

 double star ^ of the Great Bear the two parts have changed : 

 there are 14'' distance between the two stars of which it i* 

 composed. 



M. Vidal has observed at Mirepois zones of the circum- 

 polar stars which were wanting. 



M. Delambre at the summer solstice made an observation 

 pf the obliquity of the ecliptic with a multiplying circle. 

 The mean of four years observations^ and of two years made. 



by 



