108 STELLAR NUMBERS AND DISTANCES. 
sition of the equal average luster of each class of stars. Those of the 
ninth are the most closely seattered. The intervals between star and 
star widen rapidly and continuously (for the sudden dip at 9-5 magni- 
tude is evidently accidental) down to 11.5 agnitude, when a slight re- 
covery, lasting to the thirteenth magnitude, sets in. How far these 
changes are of a systematic character can only be decided from far 
wider surveys. 
