440 HE. S. Holden—Proper Motion of the Trifid Nebula M. 20. 
observing books, ee order that they may serve for future com- 
arisons. ot infrequently a verbal statement can be made 
more definite and satisfactory than the presentation of the same 
evidence in a drawing. 
Washington Observations. 
1874. August 12. Observers, S. W. Burnham and E. 8. Holden: the subsequent 
observations are by the latter observer. 
Sketch of ( made, 37 and 38 faint. Within 35” of Sh. 379 
are 4 stars, I, II (=Lassell’s ade Ill and IV. [These have been 
subsequently measured, se h, Ast. Obs. for 1874-5-7 ; of these 
I and IV were Rincoveten byl Prof. Langley at Harvard College 
earvatary, 
34 equal in brightness to 36. [The principal work of this night 
was the making of the star-chart f 
6 is certainly inside the nebulosity, but is close to its preceding 
cone: 11 is inside the nebulosity by $ of the distance from 6 to 
11, but the oe: is faint there; 12 and 13 both inside; 12 is 
nearer to the following edge of the “nebula ae 13. 52 is inside 
the eatin ?? Clouds prevent further work. 
1875. August 5. 
6 is on the edge of A. 11 is on the edge of a brighter streak, 
but follows the extreme edge by about } the distance 6-11. From 
11 to the point near the triple star [this refers to the point of the 
edge of the nebula A north of 1-2-19 and about the prolongalon 
of the line 1-2; August, 1877] the edge is faint and tremulou 
12-13-52 all inside the nebu ulosity. In the line 13-52 the cag 
to the following edge Sealy is not always sharp) is about equal 
to the distance tam 13 to 52, [This distance is to be measured 
from 52 toward the fillwinc side, 1877. 
A figure was made, from which the following notes are derived. 
The nebula is condensed around star 4. Ifa line be drawn joining 
this last line cuts ve ope edge of B at a distance from 18 
20 is about vi middle of the dark channel f [see index-map]. 
The angle of position of this channel f is 160° (1 measure). 
f extends ¢ of the distance from 20 to 9. 
ay is immersed in nebulosity. The line 20-9 [16 ?] is nearly the 
of f. 
a second sketch of the bounding lines of the nebula made, which 
agrees more nearly with Lassell 1864 than the first one of this night, 
in the position of the nebulosit mera fo the stars 18 and 40.] 
The triple star Sh. 379 is mali ia 
