E. 8. Holden— Proper Motion of the Trifid Nebula M.20. 487 
“On comparing our figures they will be found to agree in every 
essential particular, allowing for the difference of light between 
reflectors of 12 dnd 18 inches aperture, with one rather remanent 
exception, viz: in the form of the southern mass of the trifid neb- 
a and the character of the three paths or avenues which’ lead up 
the triple star. Mason represents these avenues as free e from 
ate abrupt change of direction, the northern and preceding of 
them branching out with and easy and graceful biftreation from 
N. 
Fig. 4. Index-Map. (Lassen.) 
the southern; whereas my figure, whose correctness in this respect 
I cannot ¢ oubt, gives the prec eding avenue a remarkably sudden 
and uncouth flexure, like a gnarled branch of an oak, just at its 
divergence from the other two.”*— Astron. Obser. Cape of Good 
Hope, p. 10. 
* M : = Art. 4 46, p. se this appearance | is recorded among the 
thin ght His re represents only “things certain,” and 
sieobanly. Sir po Here hel referred Saily to the drawings in his comparisons. 
