144 Royal Society : — Dr. W. Huggins on the Motions of 



the star of from 40 to 50 miles per second, to which must be added 

 3'9 miles for the earth's motion from the star. 



a Cygni. — The hydrogen line at F in the spectrum of this star 

 is narrower than in the spectrum of Sirius and of a Lyrse, though 

 probably rather broader than the same line in the solar spectrum. 

 I have at present observations made on two evenings only, on both of 

 which the state of the air was unfavourable for the comparison of this 

 line with that of terrestrial hydrogen. They give to the star a 

 motion of approach of about 30 miles per second, which would have 

 to be increased by 9 miles, the velocity at the time of the earth from 

 the star. 



Pollux. — The lines of magnesium and those of sodium are very 

 distinct in the spectrum of this star. As the air was not very steady 

 at the time of my observations, I found it more satisfactory to use 

 for comparison the lines of magnesium, which are rather stronger than 

 those of sodium. The three lines of magnesium appeared to be less 

 refrangible than the corresponding dark lines in the spectrum of the 

 star by about one- sixth of the interval from 'Mg a to Mg 3 . This esti- 

 mation would represent a velocity of approach equal to about 32 

 miles per second. The earth's motion from the star was 17*5 miles, 

 which increases the apparent velocity of approach to 49 miles per 

 second. On one evening only was the air favourable enough for 

 a numerical estimate, but the observations were entered in my ob- 

 servatory-book as satisfactory. 



a Ursce majoris. — The spectrum of this star is different from 

 the spectra of the other bright stars of this constellation. The line 

 at F is not so strong, while the lines at b are more distinct, and are 

 sufficiently strong for comparison with the bright lines of magnesium. 

 The bright lines of this metal fall on the less refrangible side of the 

 dark lines, and show a motion of approach of from 35 to 50 miles 

 per second. The earth's motion of 11 "8 miles from the star must be 

 added. 



y Leonis and s Bodtis. — In both these double stars the com- 

 pound spectrum due to the light of both component stars was ob- 

 served. Both stars are most conveniently compared with magne- 

 sium. I do not consider my observations of these stars as quite 

 satisfactory, but they seem to show a movement of approach ; but 

 further observations are desirable. 



The stars y Cygni, a Pegasi, y Pegasi, and a Andromeda were 

 compared with hydrogen on one night only. It is probable that 

 these stars are approaching the earth, but I wish to reobserve them 

 before any numerical estimate is given of their motion. 



y Cassiopeia. — On two nights I compared the bright lines which 

 are present in its spectrum at C and F with the bright lines of ter- 

 restrial hydrogen. The coincidence appeared nearly perfect in spec- 

 troscope C with eyepieces 2 and 3 ; but on the night of best definition 

 I suspected a minute displacement of the bright line towards the red 

 when compared with H /3. As the earth's orbital motion from the 

 star at the time was very small, about 3'25 miles per second, which 

 corresponds to a shift that could not be detected in the spectroscope, 



