7. A striking argument in favor of this theory may be derived from the researches of the late Professor Graham, considered in connection with those of Dr. Huggins and other eminent spectroscopists. Professor Graham found large quantities of hydrogen confined in the pores or cavities of certain meteoric masses. Now, the spectroscope has shown that the sun's rose-colored prominences consist of immense volumes of incandescent hydrogen; that the same element exists in great abundance in many of the fixed stars, and even in certain nebulæ; and that the star in the Northern Crown, whose sudden outburst in 1866 so astonished the scientific world, afforded decided indications of its presence. THE END. _BY THE AUTHOR OF THIS VOLUME._ METEORIC ASTRONOMY: A TREATISE ON SHOOTING STARS, FIRE BALLS, AND AEROLITES. BY DANIEL KIRKWOOD, LL.D. 12mo. Extra Cloth. $1.50. For sale by Booksellers generally, or will be sent by mail, postpaid, on receipt of the price by J. B. LIPPINCOTT & CO., Publishers, _715 and 717 Market St., Philadelphia_. Transcriber's Note: Obvious errors in spelling and punctuation have been corrected. Footnotes have been renumbered and moved from the page end to the end of the paragraph. Images have been moved from the middle of a paragraph to the closest paragraph break. End of the Project Gutenberg EBook of Comets and Meteors, by Daniel Kirkwood