E. 8. Holden—Proper Motion of the Trifid Nebula M.20. 485 
“A careful drawing t taken, but the nebula is not clear from twi- 
light and clouds. aaa This drawi ing is unfortunately lost, and 
that engraved in fig. 80 is constructed from much less elaborate 
sketches, aided by memor 5 32. 
“Ver large ; trifid, three nebule with a vacuity in the midst, 
in which is righ situated the double star Sh. 379.”—Phil. 
Trans., 1833, p. 
If we had nothing but the preceding evidence aes regard to 
this nebula we should be justified in laying down the following 
tpg. with regard to the situation of the triple ihe relative 
to the three nebulosities. 
8. 
N. 
Fig 2. Mason and Situ, 1839. 
4. From 1784, July 12, to 1833, this triple star was centrally 
situated habinash the three Ltacheetn f es. ‘The evidence is based upon 
two observations of Sir am Herschel and four phiseryations 
of Sir John, and in the tae Trans. for 1811-Sir William again 
repeats his former statements. 
