﻿Smithsonian 
  Report, 
  1927. 
  — 
  Abbot 
  

  

  Plate 
  8 
  

  

  The 
  Spiral 
  Nebula 
  in 
  Canes 
  Venatici. 
  (Mount 
  Wilson 
  Observatory) 
  

  

  