448 E. 8. Holden—Proper Motion of the Trifid Nebula M. 20. 
gure in the vol. xxxvi of the same series (p. 48 and fig. 32 
Plate VII), which we give below. The first of these figures 
we may, however, briefly describe in some important points, 
using Lassell’s nomenclature for the stars, as given in the last 
cited work and Mason’s nomenclature for the “nebulosity, as in 
our Index-map. 
N. 
Fig. 5. Lassen, 1862. 
Lassell’s first figure. 
I. Stars 1, 2, 19 are immersed in the nebula. 
Il. The line ‘of stars 12-13 prolonged passes through the nebu- 
losity of A. If we draw the shortest line from star 2 to the pre- 
ceding edge of A this line is cut by the line 12-13, cbonnasel at 
about one-third its length from > _— eding end, and this line is 
involved in the nebula near 1, 2, 19, for about 30’ of its length. 
Ill. The line from 14 to 20 — the line from 2 at about its 
mee point, or) is involved in the nebula near 1, 2, 19 for about 
” of its lengt 
