II. On a cause for the appearance of bright lines in the spectra of irresolvable star clusters

Before the announcement of Mr. Huggins’s discovery of the presence of bright lines in the spectra of nebulae, it was generally, if not universally, accepted as a fact that nebulae were merely stellar clusters irresolvable on account of their great distances from us. This view had become impressed on the minds of many of our greatest observing astronomers in the progress of their work, and is one therefore which should not lightly be abandoned. It appears to me that Mr. Huggins’s observations, instead of being inconsistent with the view formerly held by astronomers, are rather confirmatory of the correctness of that view.