416 SCIENTIFIC RECORD FOR ld83. 



Comet a 1882 was observed seven times on the meridian, and comet 

 b 1882, three. The routine reductions of all the observations with this 

 instrument are reported in an extraordinary state of forwardness. 

 From the beginning of this year, a correction of — 0".39, has been applied 

 to the results of the nadir observations to make them agree in the mean 

 with the results of the reflection observations of stars. This discordance 

 was insignificant in 1878, and is on the increase ; its source has not yet 

 been traced. Three determinations of flexure have been made during 

 the year. The correction for B — D, the error of assumed co-latitude, 

 and the position of the ecliptic, have been investigated for 1882. The 

 value for the co-latitude, from the observations of 1882, is 38° 31' 21".1)3. 

 The correction to the tabular obliquity of the ecliptic is +0".44. The 

 mean error of the tabular right ascension of the moon, from observa- 

 tions with the transit circle, is +0 8 .82. 



The observations of the moon with the alt-azimuth have been re- 

 stricted to the semi-lunation between last quarter and first quarter. 

 The moon's diameter has been measured thirty-three times, counting 

 measures in both co-ordinates with the transit circle and the alt-azimuth. 



A very valuable addition has been made to the instruments of the 

 Royal Observatory by the gift of the Lassell 2-foot reflecting equatorial, 

 generously presented by the Misses Lassell. This is the instrument 

 with which the Saturnian satellite Hyperion was discovered in 1848. It 

 was removed from Maidenhead early in March, and has been suitably 

 mounted in the grounds of the Boyal Observatory. The telescope has 

 two large mirrors available for use ; and the astronomer royal contem- 

 plates attaching one of them to the tube of the •' southeast equatorial," 

 which has a firm mounting and a perfect clock-work, and employing it 

 for spectroscopic and photographic work. The Lassell telescope itself 

 is well suited for the observation of faint satellites and comets which 

 are beyond the present instrumental means of the observatory. 



Spectroscopic observations of motion of stars in the line of sight have 

 been made as follows : A hundred and forty-two measures of the dis- 

 placement of the F line in the spectra of twenty-three stars, and twenty- 

 six measures of the line b x in nine stars. The observations of Sirius 

 during the past winter tend, on the whole, to confirm the impression 

 that the rate of recession of this star had diminished progressively since 

 1877, and that its motion is now on the point of being converted into 

 one of approach. 



The spectrum of comet a 1882 was examined on three nights; that of 

 the great comet b 1882, also on three nights; and that of comet a 1883, 

 on one night. The spectrum of the first-named object showed the yel- 

 low sodium lines with great brilliancy just before perihelion passage. 

 The spectrum of the aurora was also examined in 1882, November 17. 

 The spectroscopic observations of all kinds are completely reduced to 

 1883, May 20. 



During the year ending at this time, photographs of the sun were 



