burn in space. As far as observations have already gone, each star has its own individuality as to chemical composition. The line D, characteristic of sodium, has been detected in the spectra of Pollux, Capella, Beltigeux, and Procyon; and it is probable that the colour of yellow stars is due to this widely- diffused element. It is probable that there are systems where metals chiefly prevail, and others where the characteristic elements are alkalies.
This new instrument of research is by far the most comprehensive that has yet been put into man's hand. It is destined alike to deal with worlds and with atoms. It can decompose the distant star, and the invisible molecule. All science tends to bind, under the same mechanical laws, the motions of orbs and atoms. Light and heat are regarded merely as modes of motion. The elementary atoms are in a constant state of vibration; that vibration produces a vibration in the ether, and the vibration of the ether, in reaching us, is light or heat—a light vibration being merely a heat vibration, with the rate so intensified that it becomes luminous. It is exceedingly probable that the complexity of the spectrum of any elementary body is related to the complexity of the atom itself. If, for example, the spectrum of an atom, hitherto supposed to be elementary, give several colours, it is probable that there are several component atoms vibrating at different rates—corresponding to the dif-
