66 H. C. RUSSELL. 



features of Nubecula Major we see that the curves are nearly 

 circles, both those in the main body of it, and in the several star 

 clusters and nebulse ; further if we examine them very closely we 

 find that they are all slightly elongated in the same way ; or in 

 other words the major axes of these ellipses are parallel or nearly 

 so ; they all in fact seem to lie in a plane nearly at right angles to 

 the line of sight. Now just as the sun with his attendant planets, 

 the planets with their moons, and especially Saturn with his 

 rings, shew us that there has been a tendency, as theory would 

 also lead us to expect, to arrange the matter, that is revolving 

 about them in a plane common to all, and as is also evidently the 

 case with spiral nebulse, the matter is arranged in a plane of which 

 the diameter is enormously greater than the thickness, so I think 

 we may safely assume, that the Nubecula Major is a great spiral 

 structure of which we see the greatest diameter, and that its 

 thickness, measured through in the line of sight is comparatively 

 small ; further in addition to the central spiral there are two 

 nebulae, and at least three clusters of stars arranged as spirals, 

 having one character in common with the main one, that is, they 

 are nearly circular, and these are all arranged in space, so that 

 they appear to us, in the same or parallel planes, and near together. 

 It may, I think, be safely assumed that all these are parts of the 

 grandest spiral strcture that we know, and that they are all in 

 one plane, because if they are not in the same plane, then, being 

 optically close together and in parallel planes they must be 

 arranged one after the other in a long vista which happens to be 

 in our line of sight • that is, a series of great spirals, one behind 

 the other, at different distances towards infinity, and all revolv- 

 ing as if on a common or parallel axes ; a conclusion which is 

 , highly improbable, and impossible to receive when the simple and 

 more rational alternative of their being all in the same plane is 

 available, which also accords with what we see in other systems. 

 If we assume that all are in the same plane, we can imagine what 

 we should see if transported to some star near the centre. All round 

 us would be an infinity of stars, which on closer inspection, would 



