"How does this fact consist with the hypothesis that nebulæ are remote galaxies? If there were but one nebula, it would be a curious coincidence were this one nebula so placed in the distant regions of space as to agree in direction with a starless spot in our sidereal system! If there were but two nebulæ, and both were so placed, the coincidence would be excessively strange. What shall we say on finding that they are habitually so placed? (the last five words replace some that are possibly a little too strong).... When to the fact that the general mass of nebulæ are antithetical in position to the general mass of the stars, we add the fact that local regions of nebulæ are regions where stars are scarce, and the further fact that single nebulæ are habitually found in comparatively starless spots, does not the proof of a physical connection become overwhelming?"[358] With reference to the small elongated nebula discovered by Miss Caroline Herschel in 1783 near the great nebula in Andromeda, Admiral Smyth says, "It lies between two sets of stars, consisting of four each, and each disposed like the figure 7, the preceding group being the smallest."[359] Speaking of the "nebula" Messier 3--a globular cluster in Canes Venatici--Admiral Smyth says, "This mass is one of those balls of compact and wedged stars whose laws of aggregation it is so impossible to assign; but the rotundity of the figure gives full indication of some general attractive bond of union."[360] The terms "compact and wedged" are, however, too strong, for we know that in the globular clusters the component stars must be separated from each other by millions of miles! Prof. Chamberlin suggests that the secondary nebula (as it is called) in the great spiral in Canes Venatici (Messier 51) may possibly represent the body which collided with the other (the chief nucleus) in a grazing collision, and is now escaping. He considers this secondary body to have been "a dead sun"--that is, a dark body.[361] This would be very interesting if it could be proved. But it seems to me more probable that the secondary nucleus is simply a larger portion of the ejected matter, which is now being gradually detached from the parent mass. Scheiner says "the previous suspicion that the spiral nebulæ are star clusters is now raised to a certainty," and that the spectrum of the Andromeda nebula is very similar to that of the sun. He says there is "a surprising agreement of the two, even in respect to the relative intensity of the separate spectral regions."[362] In the dynamical theory of spiral nebulæ, Dr. E. J. Wilczynski thinks that the age of a spiral nebula may be indicated by the number of its coils; those having the largest number of coils being the oldest, from the point of view of evolution.[363] This seems to be very probable.