Much the same may be said of the presence of carbides. While they no longer exist on the surface, there is no doubt of their existence in the interior of the earth, and the volcanic gases contain their decomposition products. In this connection the theory--first put forward by Mendelèeff and since supported by Moissan--of the origin of petroleum, may be mentioned. These writers favor the hypothesis that it was formed by the decomposition of carbides by water under pressure; and while the evidence at hand perhaps favors the belief that the petroleum of the more important oil fields owes its origin to decomposition of the lower forms of marine animal life, yet there can be no doubt that petroleum may be formed by carbide decomposition, and it seems probable that natural gas is in part at least a result of the same action. A PRELIMINARY ACCOUNT OF THE SOLAR ECLIPSE OF MAY 28, 1900, AS OBSERVED BY THE SMITHSONIAN EXPEDITION. BY DR. S. P. LANGLEY, SMITHSONIAN INSTITUTION. Partly in deference to the report of the United States Weather Bureau, from which it appeared that the chance of a fair eastern sky on the morning of the eclipse was about 8 to 1, and after examination by Mr. Abbot of many stations in North Carolina, Wadesboro, of that State, was selected early in April as the site of the Smithsonian observations. The advantages of Wadesboro being also recognized by Professor Young, of Princeton, Professor Hale, of Yerkes Observatory, and the Rev. J. M. Bacon, of the British Astronomical Association, it came about that four large observing parties, besides several smaller ones and numerous excursionists from the surrounding country, were all joined to produce at Wadesboro one of the largest company of eclipse observers ever assembled for scientific purposes. It is a matter for congratulation that the sky at Wadesboro upon the day of the eclipse was cloudless and clearer than the average, so that the efforts of the observing forces were not thwarted by any circumstances beyond their control. The provisions of the Mayor and authorities of Wadesboro for preventing intrusion before and during the eclipse, and thus securing an undisturbed field of operations, deserve especial recognition. Further than this, the many acts of courtesy and hospitality to the visiting astronomers on the part of the townspeople will long be remembered by the recipients. The Smithsonian party proper consisted of thirteen observers, and included Mr. Langley, Mr. Abbot, aid acting in charge of the Smithsonian astrophysical observatory; Mr. Smillie, in charge of photography; Mr. Putnam, of the United States Coast Survey; Mr. Fowle, Mr. Mendenhall, Mr. Child, Mr. Draper, Mr. Gill, Mr. Kramer and Mr. Smith. Included with these, the Rev. Father Searle and the Rev. Father Woodman gave most valuable assistance. Mr. Hoxie, of Port Royal, S. C., and Mr. Little, of Wadesboro, rendered valued assistance to Mr. Putnam during totality.