THE HORSESHOE NEllilLA IS SAUlTTAlilUS. 279 



During the last summer M. Trouvelot was invited by the superin- 

 tendent of the United States Naval Observatory to visit Washington 

 for the purpose of making drawings of nebiila?, etc., by means of the 

 twenty-six inch Clark refractor. ]>y the courtesy of Admiral Davis 



I am able to give a drawing of the Horseshoe Nebula as delineated 

 by M. Trouvelot from observations made jointly by him and by 

 myself. 



Pretty much the same method w^as adopted in this drawing as in 

 Fig. 6, but the vastly more complex structure of the nebula itself is 

 what might have been expected from an increase of eighteen times in 

 the light, over M. Trouvelot's six-inch telescope. 



