416 POPULAR SCIENCE MONTHLY. 



and 25° to 29° of declination, an area of 10°. 5. This existence of 

 seven lucid stars within so small an area suggests that they belong to- 

 gether, and may have smaller stars belonging to the group, and making 

 the star-density of this area greater than that of the sky in general. 



The question whether there is any corresponding excess of richness 

 in the fainter stars will be decided by a count of those contained in 

 Graham's section of the A. G. Catalogue, which extends to the ninth 

 magnitude. With the area above defined this catalogue gives seventy- 

 one stars. Subtracting the seven lucid stars, we have sixty-four small 

 stars left within the area. To the same belt of declination 33G stars 

 are listed in the twelfth hour of E. A., giving an average of sixty-seven 

 stars to an area equal to that of the cluster. The small stars are, there- 

 fore, no thicker within the area of the cluster than around it. It may 

 be added that the seven lucid stars do not seem to have any common 

 proper motion, so that their proximity is probably an accident. 



Prcesepe. — This object, situate in the constellation Cancer, appears 

 to the naked eye as a patch of nebulous light. It is actually a con- 

 densed group of stars, of which the brightest are of the seventh magni- 

 tude. The stars of the ninth magnitude included within the area of 

 the group probably belong, for the most part, to it, but they are too 

 few to serve as the base for any positive conclusion. 



Orion. — I find by measurement and count that a circle 20° in 

 diameter, comprising the brightest stars of this constellation, contains 

 eighty stars to magnitude (3.3. Of these six are of the first or second^ 

 leaving seventy-four from the third to the sixth. The resulting rich- 

 ness is 24 to 100 square degrees, about the average richness along the 

 borders of the galaxy. It follows that this remarkable collection of 

 bright stars has no unusual collection of faint stars associated with it. 



A very natural inquiry is whether the bright stars in Orion have any 

 common proper motion, indicating that they form a system by them- 

 selves. The answer is shown in the following statement of the proper 

 j not ions in a century: 



Proper Motions. 

 Star. Mag. K. A. Dec. 



Eigel 1 +0.1 0.0 . 



?; Orionis 3 -f 0.1 —0.3 



y Orionis 2 —0.6 —1.7 



S Orionis 2 0.0 —0.2 



€ Orionis 2 0.0 +0.1 



(? Orionis 2 0.0 —1.4 



a: Orionis 2 +0.1 -0.3 



a Orionis 1 +30 +0.9 



For the most part these motions are too small to be placed beyond 

 doubt, even by all the observations hitherto made. In the case of 



