1. 1731, March 12th. At Halstead, Essex, England. 2. 1798, March 12th. At Salés, France. 3. 1806, March 15th. At Alais, France. 4. 1807, March 13th. At Timochin, Russia. 5. 1811, March 13th. At Kuleschofka, Russia. 6. 1813, March 13th-14th. The phenomena above described. 7. 1841, March 12th. At Grüneberg, Silesia. Numerous fire-balls have appeared at the same epoch. [20] The innermost or semi-transparent ring of Saturn appears to be similarly constituted, as the body of the planet is seen through it without any distortion whatever. [21] Origin of the Stars, p. 173. [22] Origin of the Stars, p. 184. [23] Since the above was written Prof. Ennis has informed the author that, without making any estimate of his own, he adopted the density of Jupiter's first satellite as given in Lardner's _Handbook of Astronomy_. [24] Origin of the Stars, p. 77. [25] Youman's Correlation and Conservation of Forces, p. 244. [26] Iowa Instructor and School Journal for November, 1866, p. 49. [27] A recent hypothesis in regard to the temporary star of 1572 has been proposed by Alexander Wilcocks, M.D., of Philadelphia. See Journ. Acad. Nat. Sci. of Phila. for 1859. [28] Gautier's Notice of Recent Researches relating to Nebulæ.--Silliman's Journal for Jan. 1863, and March, 1864. [29] Outlines of Astronomy, Art. 442. [30] A learned and highly interesting examination of this hypothesis will be found in a memoir "On the Secular Variations and Mutual Relations of the Orbits of the Asteroids," communicated to the Am. Acad. of Arts and Sciences, April 24th, 1860, by Simon Newcomb, Esq. [31] For an explanation of the origin of the asteroids according to the nebular hypothesis, see an article by David Trowbridge, A.M., in Silliman's Journal for Nov. 1864, and Jan. 1865. [32] H. C. Sorby, F.R.S. [33] Harte's Trans. of Laplace's Syst. of the World, vol. ii., note vii. [34] Grant's Hist. of Phys. Astr., p. 302. [35] Nos. 1632 and 1633. PUBLICATIONS OF J. B. LIPPINCOTT & CO., Phila. _Will be sent by Mail, post-paid, on receipt of price._ NEW AMERICA. By WILLIAM HEPWORTH DIXON, Editor of "The Athenæum," and author of "The Holy Land," "William Penn," etc. With Illustrations from Original Photographs. Third Edition. Complete in one volume, Crown Octavo. Printed on tinted paper. Extra Cloth. Price $2.75. In these graphic volumes Mr. Dixon sketches American men and women, sharply, vigorously, and truthfully, under every aspect. The smart Yankee, the grave politician, the senate and the stage, the pulpit and the prairie, loafers and philanthropists, crowded streets and the howling wilderness, the saloon and the boudoir, with women everywhere at full length--all passes on before us in some of the most vivid and brilliant pages ever written.--_Dublin University Magazine._ ELEMENTS OF ART CRITICISM.