The element helium (No. 2) was first discovered by Lockyer in the sun, and not until many years later was it found on the earth. Astrophysicists are not likely to repeat this achievement; they cannot discover new elements if there aren’t any. The unknown source of the two rings close together on the right of the photograph (a bright ring and a fainter ring) has been called _nebulium_. But nebulium is not a new element. It is some quite familiar element which we cannot identify because it has lost several of its electrons. An atom which has lost an electron is like a friend who has shaved off his moustache; his old acquaintances do not recognize him. We shall recognize nebulium some day. The theoretical physicists are at work trying to find laws which will determine exactly the kind of light given off by atoms in various stages of mutilation--so that it will be purely a matter of calculation to infer the atom from the light it emits. The experimental physicists are at work trying more and more powerful means of battering atoms, so that one day a terrestrial atom will be stimulated to give nebulium light. It is a great race; and I do not know which side to back. The astronomer cannot do much to help the solution of the problem he has set. I believe that if he would measure with the greatest care the ratio of intensity of the two nebulium lines he would give the physicists a useful hint. He also provides another clue—though it is difficult to make anything of it--namely, the different sizes of the rings in the photograph, showing a difference in the distribution of the emitting atoms. Evidently nebulium has a fondness for the outer parts of the nebula and helium for the centre; but it is not clear what inference should be drawn from this difference in their habits.