A. MATHEMATICS AND ASTRONOMY. 19 



the position-angle from measures taken from January 3 to 

 April 8, as follows : 



Hall (G nights) ;>=55.22" 



Holden (6 nights) p == 54.53^ 



Mean r>4:.88 



The distance is still greater than 11". 



Lassell's new companion (more properly Marth's, as Lassell 

 did not observe it; see Mem. R. A. /S., vol. xxxvi., p. 38) was 

 seenby Mr.Erck^:=:130,6'='75". Marth's measure of 1865, 

 Jan. 14, gave p=127, s=60"dz. 12 A, March 30, 1876. 



THE VARIABLE STAR BETA PERSEI (aLGOl). 



Dr. Julius Schmidt, Director of the Observatory of Athens, 

 in continuance of his publication of the results of his long- 

 continued observations of variable stars, has announced the 

 definitive results of a thirty years' series (1845-1875) of ob- 

 servations on the variability oi Algol. In the thirty years 

 285 minima have been observed, or an average of more than 

 nine each year, and it is especially noteworthy that there is 

 not a single year without at least three observations. These 

 observations have been steadily pursued, whether at Bonn, 

 Hamburg, Olmiitz, in Greece, or at sea, with veritable assi- 

 duity. Argelander and Schonfeld have also carefully fol- 

 lowed up this star, and Schmidt finds for the probable error 

 of a single determination (of the time of minimum) 



Argelander p. e. = 0.0-4'" from 50 observations. 



Schmidt " =8.0?. " 183 " 



Schonfeld " =4.50'" " 55 '" 



Combination of all observers.. " ==7.0U'> " 288 " 



As an indication of the constant differences of these three 

 observers, Schmidt deduces from simultaneous observations: 



Schmidt Argelander^- 3.89"" 1.72'", from 21 observations (184:0-58). 

 " Schonfeld =-0.79'"2.G8"\ "17 " (1855-75). 



The final result for the period of Algol is 2 days, 20 hours, 

 48 min., 53.60 sec 38 C, No. 2077. 



THE MOTION OF STARS TOWARD OR FROM THE EARTH. 



It is known that the method of determinino; the motion of 

 stars toward or from the earth by means of the displacement 

 of a line in the spectrum of the star relatively to the position 



