The resolvable knot in the eastern portion of the bright branch, which is, in a considerable degree, insulated from the surrounding nebula; strongly suggesting the idea of an absorption of the nebulous matter; and, 2.

The much feebler and smaller knot at the northwestern end of the same branch, where the nebula makes a sudden bend at an acute angle.A second, more detailed sketch was made during his visit to South Africa in 1837.

The nebula was also studied by Johann von Lamont and separately by an undergraduate at Yale College, Mr Mason, starting from around 1836.

The nebulous diffusion, too, at the [western] end of that arc, forming the [western] angle and base-line of the capital Greek omega (Ω), to which the general figure of the nebula has been likened, is now so little conspicuous as to induce a suspicion that some real change may have taken place in the relative brightness of this portion compared with the rest of the nebula; seeing that a figure of it made on June 25, 1837, expresses no such diffusion, but represents the arc as breaking off before it even attains fully to the group of small stars at the [western] angle of the Omega.

Mr. Mason ... expressly states that both the nebulous knots were well seen by himself and his coadjutor Mr. Smith on August 1, 1839, i.e., two years subsequent to the date of my last drawing.

Neither Mr. Mason, however, nor any other observer, appears to have had the least suspicion of the existence of the fainter horseshoe arc attached to the [eastern] extremity of Messier's streak.

4], the nebulous diffusion at the [western] angle and along the [western] base-line of the Omega is represented as very conspicuous; indeed, much more so than I can persuade myself it was his intention it should appear.Sketches were also made by William Lassell in 1862 using his four-foot telescope at Malta, and by M. Trouvelot from Cambridge, Massachusetts, and Edward Singleton Holden in 1875 using the twenty-six inch Clark refractor at the United States Naval Observatory.