THE SUN AND FIXED STARS. 191 



over an angle of one third of a second, if seen at right 

 angles from the average distance of a star of the first 

 magnitude. If we assume the parallax of such a star as 

 equal to one fifth of a second, we shall find that the sun 

 advances through space, carrying with it the whole 

 system of planets and comets, with a velocity about one 

 fourth of the earth's annual motion in its orbit. 



A great many questions here naturally suggest them- 

 selves. Is the sun's motion uniform and rectilinear, or 

 is it moving slowly in an orbit about some center ? Are 

 the stars moving in straight lines, or in grand orbits? 

 Have all the stars, including our sun, a common move- 

 ment of rotation about some general center? This ques- 

 tion has been examined by Professor Madler of the 

 Dorpat observatory, and he has attempted to assign the 

 center round which the sun and stars revolve, which 

 center he places in the group of the Pleiades. 



If we assume that the orbit described by our sun 

 about the central point is a circle, this central point must 

 be found on the circumference of a great circle, whose 

 pole is that point toward which the sun is moving, in 

 right ascension 259^, declination 34 north. This circle 

 cuts the Milky Way in the constellation Perseus, and 

 Argelander conjectured the central point to be here in 

 Perseus. The most remarkable cluster of stars in this 

 neighborhood is the Pleiades, and Madler conjectured 

 that here might be the central point. Accordingly he 

 determined the proper motion of the eleven principal 

 stars in this cluster by comparing the observations of 



