Page:Popular Science Monthly Volume 6.djvu/554

536 be installed at the same time with a meridian circle of very large dimensions. Under a sky of exceptional transparency these fine instruments will serve for important researches in the hands of an experienced astronomer, Mr. Marth, the former assistant of Mr. Lassell.

The question of the constitution of nebulæ entered upon a new phase by the appearance of spectrum analysis among the methods applicable to the study of celestial bodies. Since 1869, Messrs. Huggins and Miller have concentrated all their efforts upon this department of research. They have discovered that the unresolvable nebulæ are masses of incandescent gas—they are suns in process of formation; while the resolvable nebulæ are masses of solid matter, hosts of suns already formed. It has also been established by the aid of the spectroscope that comets have a light of their own independent of that which comes from the sun, and is reflected by these wandering stars. These discoveries will give to the little observatory of Upper Tulse Hill an honorable mention in the history of astronomy.

On his side, Mr. Norman Lockyer, at Hampstead, devotes himself to the spectroscopic study of the sun. He sought for a long time to discover a process for observing in a regular manner the rosy protuberances on the solar border, which had thus far been seen only during total eclipses. Hoping that the spectroscope would betray the presence of the red flames on the contour of the star at ordinary times, Mr. Lockyer constructed an apparatus of several prisms, and in October, 1868, succeeded in discovering the traces of a protuberance in the spectrum of the solar border. Two months previous, M. Janssen, a French astronomer, who went to India to observe the total eclipse of the 19th of August, was in possession of an analogous method for the study of protuberances, but the announcement of his discovery reached Europe on the very day when Mr. Lockyer announced his own to the scientific world. By enlarging the slit of the spectroscope, the red flames can be seen directly, and the rapid changes followed. Astronomers now draw them at any time. Two years since, Mr. Lockyer succeeded in producing artificial eclipses of the sun by the interposition of a copper disk, which plays the rôle of the moon in eclipses, and he thus obtained several drawings of the solar atmosphere with all its minute details.

Mr. Carrington, at Redhill, has chosen another specialty; he has devoted eight years to a long series of observations of solar spots, which have led to remarkable conclusions relative to the constitution of the sun: the unequal velocity of rotation of the different regions of the solar globe would prove the existence of immense currents in the atmosphere of this star. The observatory of Mr. Isaac Fletcher, at Tarn-Bank, Cumberland, was created for the systematic study of double stars, a study which had also for many years occupied the attention of Admiral Smyth, at the observatory of Hartwell, where he was