1872.] 



some Stars towards or from the Earth. 



389 



means of spectroscope C and eyepieces 2 and 3. The line of terrestrial 

 hydrogen falls above the middle of the line in the star ; the star is there- 

 fore receding from the earth. The velocity of recession may be estimated 

 as rather smaller than Sirius, probably about 30 miles per second, the 

 earth at the time of observation moving from the star with a velocity of 

 15 miles, leaving about 15 miles as due to the star. This estimate is pro- 

 bably rather smaller than the true velocity of the star. 



Castor. — The spectra of the two component stars of this double star 

 blend in the spectroscope into one spectrum. The line H /3 is rather broad, 

 nearly as much so as the same line in the spectrum of Sirius. 



The narrow line of rarefied hydrogen was compared in spectroscope B 

 with eyepiece 3 ; it appeared to fall on the more refrangible side of the 

 middle of the line in the star, leaving more of the dark line on the side 

 towards the red. The shift seemed to be rather greater than that in 

 Sirius, and may probably be taken at from 40 to 45 miles per second ; but 

 the earth's orbital motion was nearly 1 7 miles from the star, thu sleaving 

 about 25 miles for the apparent velocity of the star. This result rests at 

 present on observations on one night only, but they seemed at the time to 

 be satisfactory. 



Regulus. — The line at F rather broad. The corresponding line of 

 hydrogen falls on the more refrangible side of the middle of the dark line 

 in the star. The air was unfavourable on all the evenings of comparison ; 

 a rough estimate gives a velocity of from 30 to 35 per second. The earth's 

 motion was 18 miles, leaving from 12 to 17 miles for the velocity of re- 

 cession between the star and the sun. 



p and 6 Leonis. — These stars were compared with hydrogen ; they appear 

 to be moving from the earth, but the want of steadiness in the air prevented 

 me from making a satisfactory estimate of their velocity. I suspected their 

 motion to be rather smaller than that of Regulus. 



/3, y, e, 'C Ursa majoris. — All these stars have similar spectra, in which 

 the line F is strong, though there are small differences in the breadth of 

 the line. They were compared with hydrogen, and appear to be moving 

 from our system with about the same velocity. Probably their motion may 

 be taken to be not far from 30 miles per second. The earth's motion at 

 the time of observation was from 9 miles to 13 miles from these stars, leaving 

 a probable velocity of recession of 17 to 29 miles per second. In the case 

 of the double star £, the spectrum consisted of the light of both stars. 



7] Ursa majoris was also compared with hydrogen. I believe it shows a 

 motion from the earth, but the observations of this star are at present less 

 satisfactory. 



a. Virginia and a Corona? borealis. — These stars were compared with 

 hydrogen. I suspect that they are receding, but I have not had nights 

 sufficiently fine to enable me to make satisfactory observations of these 

 stars. 



In addition to these stars some observations (which are less satisfactory 



