The great nebula on the sword handle of Orion was then examined. The spectrum of the light from the brightest parts of this nebula, near the trapezium, was crossed by three bright lines, in all respects similar to those on the spectra of the planetary and other nebulæ. Other portions of the great nebula were then brought successively under examination, but the spectra of the whole of those portions which still were sufficiently bright for this method of observation remained unchanged, and exhibited the three bright lines only. The whole of the great nebula, as far as it lay within the power of Mr. Huggins’ instrument, emits light which is identical in its characters; the light from one part differs from the light from another part in intensity alone. The brighter portions of this nebula have been to a certain extent resolved into stars, by the powerful telescopes of Lord Rosse and Professor Bond, of the United States of America; the whole, or the greater part, of the light from that portion of the nebula must therefore be regarded as the united radiation of numerous stellar points. The spectrum of this radiation being crossed by the three bright lines reveals its gaseous source; Mr. Huggins therefore infers that at least some of these stellar points are merely denser parts of a gaseous matter, and that the nebulæ which he examined are enormous gaseous systems. The spectrum of the great nebula in Orion was subsequently examined by Padre Secchi. He describes the light of the spectrum as of a uniform green, crossed by three bright lines; one tolerably wide and perfectly sharp, a very slender one close to it, and the third at a little distance from the latter. This spectrum afforded a striking contrast to the spectra of the small stars in the brighter parts of the nebula. As soon as the light from one of these stars entered the slit of the instrument, its continuous spectrum was seen to flash across the field of vision in a long coloured band. This shows that the mass of matter in this immense nebula is in a different state from that of the stars themselves, as Mr. Huggins had already observed. Padre Secchi does not draw any inference from his observations as to the structure of nebulæ in general, probably thinking it premature, but he expresses astonishment at their results.