Page:Popular Science Monthly Volume 5.djvu/279

Rh Mr. Lassell's drawing (Fig. 6) exhibits the same characteristics as Herschel's in one respect. He has noted some very faint stars, particularly one, of which we will speak further, but he has omitted others much brighter (at least, brighter in 1874, and also brighter when mapped by Bond in 1865). We must attribute this to a desire to depict the form of the nebula itself, and a neglect of the stars in comparison; and yet this is difficult to do, since Lassell has given us a map of new stars which he found, some of which have never been seen by any observer since, and presumably do not exist, or have vanished. Lassell, again, finds no trace of resolvability in this nebula.



It will be noticed that Lassell has a large number of small stars above and to the left of the trapezium. These are put in the map by eye-estimates of their position, and it is somewhat difficult to identify them with Bond's stars in this place, but I have no doubt that all of them are real. Lassell's b and g have never been seen by any later observer, and probably they do not exist, a' of Lassell's map was not even noted by him as a new discovery, but it remained unseen even by the keen vision of Bond and Struve, until the mounting of the great Alvan Clark refractor (18 1/2 inches aperture) in 1862, when Alvan Clark, Jr., found this star by the aid of that instrument.

His observation has been verified by the great Clark refractor, at Washington (26 inches aperture).

In 1848, Mr. W. C. Bond, Director of Harvard College Observatory, made, by the aid of the 15-inch refractor, a map and a drawing