Page:Popular Science Monthly Volume 5.djvu/273

Rh Le Gentil, which was drawn in 1758, and which may be found in "Histoire de l'Académie," 1759. This is Fig. 2.

The fourth star was, however, seen by Domenique Cassini before Le Gentil's drawing was made.

Not a little is to be learned from these figures, which we must try to keep in mind, as the region to which they refer is the central and most interesting portion of the great nebula. We can see, first, that



there is an entire absence of shading in the portion of the nebula drawn; the outline of nebulous matter is simply filled in by shading of a uniform tint. It is much to be regretted that it is impossible to print here the exquisite engraving of this nebula, made from drawings by Prof. G. P. Bond, director of Harvard College Observatory, in 1865. In this drawing one hardly knows which to admire most, the accuracy and painstaking skill of the astronomer, or the exquisite tact of the engraver. There are very few nights so fine, and there are very few instruments so perfect, as to give a view of this nebula as good and as detailed as may be had from this engraving alone.

But we must be content with referring to the plate ("Annals of Harvard College Observatory," vol, v.) for the details of the nebulous portions of this region, and we must content ourselves with reproducing only the stars of the surrounding space. It is true that especial attention has been paid by some astronomers to the smaller stars in this nebula; while some, as Herschel the younger, have evidently bestowed more care upon the grades of light in the nebula itself; but,